Electrolyte for aqueous manganese-based battery, preparation method of electrolyte, battery and application

Abstract

The invention discloses an electrolyte for an aqueous manganese-based battery. The electrolyte comprises an electrolyte, and the electrolyte comprises a manganese salt; the weak acid is used for regulating and controlling proton dynamic release of the positive electrode / electrolyte interface to realize on-demand supply of protons of the positive electrode / electrolyte interface; and a solvent, wherein the solvent is deionized water; the PH range of the electrolyte is 2.0-3.5, and the electrolyte can realize on-demand supply of protons of a positive electrode / electrolyte interface in the charging and discharging process of the aqueous manganese-based battery, and promotes efficient and reversible deposition and dissolution reaction of a positive active substance manganese dioxide. According to the invention, the proton on-demand supply electrolyte is constructed by utilizing dynamic dissociation equilibrium of weak acid, so that on-demand supply of protons in the MnO2 dissolving process is realized, complete electrochemical dissolution of MnO2 is promoted, and generation of'dead manganese 'is inhibited, so that the cycling stability of the battery and the utilization efficiency of active substances are remarkably improved. The invention also discloses an aqueous manganese-based battery for realizing on-demand supply of protons and application of the aqueous manganese-based battery in the field of secondary energy storage.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to an electrolyte for aqueous manganese-based batteries, its preparation method, the battery, and its application. Background Technology

[0002] Driven by the global energy transition and the "dual carbon" goal, energy storage technology has become crucial for building a clean energy system. Currently, lithium-ion batteries, which dominate the electrochemical energy storage market, are widely used in consumer electronics and electric vehicles due to their high energy density and long cycle life. However, their high cost, dependence on specific resources, and safety risks such as the flammability and explosiveness of organic electrolytes significantly limit their further expansion and application in large-scale grid-scale energy storage systems. Therefore, to meet the ever-growing demand for large-scale energy storage, developing novel electrochemical energy storage technologies that are intrinsically safe, low-cost, environmentally friendly, and resource-rich has become particularly urgent and important.

[0003] Aqueous batteries are considered an ideal candidate technology for large-scale electrochemical energy storage due to their inherent high safety from the non-flammable electrolyte, low cost, environmental friendliness (being green and non-toxic), and the high abundance of key active materials (such as manganese) in the Earth's crust. In particular, aqueous manganese-based batteries, especially those utilizing the deposition / dissolution reaction of manganese dioxide (MnO2) (Mn... 2+ MnO2, as a cathode energy storage mechanism, shows broad application prospects.

[0004] However, despite its promising prospects, aqueous manganese-based batteries based on the MnO2 deposition / dissolution mechanism still face severe challenges in practical applications, mainly manifested in poor electrochemical reaction reversibility and poor cycle stability. The fundamental reason lies in the dynamically changing microenvironment requirements at the electrode / electrolyte interface during charge-discharge (i.e., MnO2 deposition and dissolution). Especially during MnO2 dissolution (discharge), the contradiction in proton demand and the slow reaction kinetics often lead to incomplete MnO2 dissolution, forming low-valence manganese-based compounds or other electrochemically inert "dead manganese" species. The continuous generation and accumulation of these "dead manganese" species severely reduces the utilization rate of active materials, impairing the battery's cycle life and overall performance. Therefore, improving the reversibility of the manganese dioxide deposition / dissolution reaction, especially solving the "dead manganese" problem, is a key challenge for the further development of this technology. Summary of the Invention

[0005] The present invention aims to solve the technical problems in the aforementioned related technologies.

[0006] Therefore, one objective of this invention is to provide an electrolyte for aqueous manganese-based batteries that enables on-demand proton supply. This electrolyte, through a design and use of a "proton valve" based on the dissociation equilibrium of a weak acid, utilizes the dynamic dissociation equilibrium of the weak acid at the electrode / electrolyte interface (co-regulated by Le Chatelier's principle and molecular polarization effects) to achieve on-demand proton supply. More importantly, through precise on-demand proton supply, this system enables highly efficient and nearly complete electrochemical dissolution of manganese dioxide, significantly reducing the formation of "dead manganese," thereby overcoming the key development bottlenecks of short cycle life and poor reversibility in aqueous manganese-based batteries.

[0007] Another object of the present invention is to provide a method for preparing the electrolyte as described above.

[0008] Another objective of this invention is to provide an aqueous manganese-based battery that enables on-demand proton supply. This battery uses a manganese-based compound as the positive electrode active material and an electrolyte containing manganese salts and a proton valve-like function, and is adapted to different negative electrodes. Through the proton (H+) in the electrolyte... + The on-demand supply design significantly improves the electrochemical dissolution efficiency of MnO2, solves the problem of "dead manganese" generation in traditional manganese-based batteries, and thus improves the reversibility of the positive electrode electrochemical reaction, the utilization rate of active manganese and the cycle life of the battery.

[0009] Another object of the present invention is to propose an application of the above-mentioned electrolyte and battery in the field of secondary energy storage.

[0010] The relevant terms used in this invention are explained below.

[0011] Aqueous manganese-based batteries: Energy storage devices that use aqueous solutions as electrolytes, manganese-based compounds (such as manganese dioxide) as positive electrode active materials, and metals (such as zinc) or non-metallic materials (such as sulfur) as negative electrode materials.

[0012] Manganese dioxide cathode energy storage mechanism: In aqueous batteries using manganese dioxide as the positive electrode active material, the working principle of manganese dioxide cathode energy storage is through single-electron intercalation (such as Zn). 2+ H + (such as embedding between manganese dioxide layers or within the lattice) or two-electron conversion (Mn) 2+ (Redox reaction between MnO2).

[0013] Manganese dioxide deposition / dissolution mechanism: refers to the Mn deposition / dissolution process that occurs at the manganese dioxide cathode during charging and discharging. 2+ Ion oxidation deposition to MnO2 and MnO2 reduction dissolution to Mn 2+The electrochemical reaction process of ions, specifically, in aqueous manganese-based batteries based on this mechanism, carbon cloth or carbon felt is usually used as the positive electrode current collector. Manganese dioxide, the positive electrode active material, is obtained by in-situ deposition on the current collector in an electrolyte containing manganese ions through electrodeposition.

[0014] "Dead manganese": During the dissolution or transformation of manganese dioxide, due to incomplete dissolution or side reactions (such as Mn), 3+ The disproportionation reaction forms manganese-based compounds with low or no electrochemical activity (such as MnO2 that has lost its electrical contact, or MnOOH intermediates that have not been fully dissolved), leading to the loss of active materials and the degradation of battery performance.

[0015] "Proton supply on demand": For the dissolution of manganese dioxide, the dissolution reaction pathway is closely related to the interfacial proton supply. Complete electrochemical dissolution of manganese dioxide can only occur when the interfacial proton supply rate matches the electrochemical reaction (electron supply) rate. If the interfacial proton rate is too fast or too slow, side reactions detrimental to the target reaction of complete electrochemical dissolution of manganese dioxide will occur. Therefore, "proton supply on demand" specifically refers to the protons captured by the proton valve in the electrolyte during MnO2 electrodeposition; when protons are needed for MnO2 dissolution, the proton valve in the electrolyte supplies protons at the positive electrode / electrolyte interface, and the proton supply rate matches the electrochemical reaction (electron supply) rate; there is no situation where there are too many or too few protons at the interface that cannot match the electrochemical reaction rate.

[0016] "Proton valve": In the electrolyte, the dissociation equilibrium of a weak acid is used to regulate the protons at the interface throughout the entire process. When the electrochemical process requires protons, the dissociation equilibrium of the weak acid shifts to the right to release protons. When the proton concentration in the electrolyte is too high or a large number of protons are generated, the equilibrium shifts to the left, thereby achieving dynamic regulation of protons at the positive electrode / electrolyte interface.

[0017] The energy storage mechanism of the manganese dioxide cathode involved in the technical solution of this invention is a MnO2 deposition / dissolution mechanism involving two-electron conversion.

[0018] According to the applicant's research, the proton concentration in the electrolyte is one of the key factors determining whether and how the MnO2 dissolution reaction can proceed smoothly. Acidic electrolytes can effectively promote the dissolution of manganese dioxide, and the proton concentration in the electrolyte is a key factor regulating the MnO2 dissolution reaction. The main reaction pathways that promote MnO2 dissolution under acidic conditions include:

[0019] MnO2 conversion: MnO2 + H+ + +e - →MnOOH;

[0020] Electrochemical dissolution of MnOOH: MnOOH + 3H₂O + +e- →Mn 2+ +2H2O;

[0021] Chemical dissolution of MnOOH: MnOOH + 3H₂O + →Mn 3+ +2H2O;

[0022] Mn 3+ Electrochemical reduction: Mn 3+ +e - →Mn 2+ ;

[0023] "Dead manganese" formation: 2Mn 3+ +2H₂O→MnO₂+Mn 2+ +4H + .

[0024] The dissolution pathway of MnOOH (electrochemical dissolution vs. chemical dissolution) is crucial to the utilization rate of manganese. Ideally, MnOOH should be completely converted to Mn through electrochemical dissolution. 2+ However, excessive proton supply (such as in a strong acid environment) will accelerate the chemical dissolution of MnOOH, producing a large amount of unstable Mn. 3+ These Mn 3+ Once diffused away from the electrode surface and loses electrical contact, it is highly susceptible to disproportionation reactions that generate "dead manganese," leading to the loss of active material. Conversely, insufficient proton supply inhibits the electrochemical dissolution of MnOOH, causing the reaction to stop at the single-electron conversion from MnO2 to MnOOH, thus preventing high-capacity release. Therefore, precisely controlling the proton supply to match the demand for electrochemical dissolution (i.e., "on-demand supply") is crucial for achieving highly reversible MnOOH dissolution. 2+ The core of MnO2 deposition / dissolution reaction, avoiding the formation of "dead manganese", and improving battery cycle life and energy efficiency.

[0025] Due to the importance of acidic conditions for the dissolution of MnO2, strong acids (such as HCl and H2SO4) are commonly used in existing technologies to provide protons. However, as mentioned above, this strategy has an inherent contradiction: while strong acid electrolytes can provide a large number of protons, they also easily lead to the rapid chemical dissolution of the reaction intermediate MnOOH, generating a large amount of Mn. 3+ This can trigger a disproportionation reaction, forming "dead manganese," which actually reduces reversibility. If the concentration of strong acid is reduced to slow down chemical dissolution, insufficient proton supply may occur during continuous discharge, inhibiting electrochemical dissolution and similarly leading to a decrease in capacity and accumulation of "dead manganese."

[0026] Therefore, based on the above research, in order to solve the technical problems in the prior art, the applicant proposes an electrolyte and battery that can realize a proton on-demand supply strategy. By utilizing the dynamic dissociation equilibrium of weak acid at the electrode / electrolyte interface (co-regulated by Le Chatelier's principle and molecular polarization effect), the "on-demand supply" of protons is realized.

[0027] In one aspect of the invention, an electrolyte for an aqueous manganese-based battery that enables on-demand proton supply is provided. The electrolyte comprises:

[0028] Electrolytes, including manganese salts;

[0029] A weak acid is used to regulate the dynamic release of protons at the positive electrode / electrolyte interface, thereby enabling on-demand supply of protons at the positive electrode / electrolyte interface.

[0030] and a solvent, wherein the solvent is deionized water;

[0031] The pH range of the electrolyte is 2.0-3.5;

[0032] During the charging and discharging process of the battery, the electrolyte can provide protons to the positive electrode / electrolyte interface on demand, promoting the efficient and reversible deposition and dissolution reaction of manganese dioxide, the positive electrode active material.

[0033] As a further improvement to the technical solution, the pH range of the electrolyte is preferably 2.1-2.8, and most preferably 2.2-2.4.

[0034] As a further improvement to the technical solution, the pKa of the weak acid is in the range of 3.0-6.0, preferably 3.5-5.5, and most preferably 3.8-5.0.

[0035] As a further improvement to the technical solution, in the electrolyte, the anions in the weak acid and the manganese ions in the manganese salt are in a non-coordinate relationship; the manganese salt is a non-coordinate anionic manganese salt.

[0036] As a further improvement to the technical solution, in the electrolyte, the stability constant logK of the complex between the anion in the weak acid and the manganese ion in the manganese salt is ≤9; the stability constant logK of the complex between the anion in the manganese salt and the manganese ion is ≤9.

[0037] As a further improvement to the technical solution, the weak acid includes one or more of acrylic acid, formic acid, acetic acid, propionic acid, glycolic acid, and ascorbic acid.

[0038] As a further improvement to the technical solution, the manganese salt includes one or more of manganese sulfate, manganese chloride, manganese perchlorate, manganese nitrate, and manganese bis(trifluoromethanesulfonate).

[0039] As a further improvement to the technical solution,

[0040] The concentration of the manganese salt in the electrolyte is 0.005-6.0 M, where M represents mol / L.

[0041] As a further improvement to the technical solution, the concentration of the manganese salt in the electrolyte is preferably 0.3-3.0M, more preferably 0.5-2.0M.

[0042] As a further improvement to the technical solution, the electrolyte satisfies at least one of the following conditions:

[0043] The electrolyte also includes a second soluble electrolyte salt, the type of which depends on the type of negative electrode that is matched with the positive electrode of the manganese-based battery.

[0044] The concentration of the second soluble electrolyte salt is 0–3.0 M;

[0045] The electrolyte also includes optional additives.

[0046] The technical solution of this invention adopts a proton-on-demand electrolyte design strategy, which introduces a weak acid dynamic dissociation equilibrium with a suitable pKa range into the electrolyte. Achieving "on-demand supply" of protons under specific acidic conditions, combined with the main reaction pathway that promotes the dissolution of MnO2 under acidic conditions, yields the following specific technical effects:

[0047] First, it inhibits the chemical dissolution of MnO2: When there is no proton requirement during static standing, the low degree of dissociation of the weak acid allows free H+ in the solution to remain in the solution. + Maintaining the concentration at a low level effectively avoids the rapid chemical dissolution of MnOOH caused by excessive protons and subsequent Mn2+ dissolution. 3+ The disproportionation reaction inhibits the production of "dead manganese" at its source;

[0048] Second, supplying protons on demand promotes the electrochemical dissolution of MnO2: During the discharge (MnO2 dissolution) process, as the interfacial H... + Consumed by electrochemical reactions, according to Le Chatelier's principle, the dissociation equilibrium of a weak acid will shift towards the formation of H+. + The direction of movement is shifted. Simultaneously, according to molecular polarization theory, the electric field at the interface lowers the dissociation energy barrier of the weak acid molecule, further accelerating its release of H₂ when needed. + ;

[0049] Third, the synergistic effect enables efficient and reversible dissolution of MnO2: the synergistic effect of Le Chatelier's principle and molecular polarization effect ensures that protons can be precisely matched to meet the requirements of complete electrochemical dissolution of MnO2, which not only ensures the full progress of the reaction, but also avoids side reactions and loss of active substances caused by excessive or insufficient protons.

[0050] In another aspect of the invention, a method for preparing the electrolyte as described above is provided. The method includes: dissolving a manganese salt in deionized water to form a manganese salt aqueous solution; adding one or more weak acids to the manganese salt aqueous solution; adjusting the final pH of the solution to 2.0-3.5 using the weak acids; and stirring until homogeneous to obtain the electrolyte.

[0051] In another aspect of the invention, the invention provides an aqueous manganese-based battery that enables on-demand proton supply, the battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte is an aqueous manganese-based battery electrolyte as described above.

[0052] As a further improvement to the technical solution, the battery satisfies at least one of the following conditions:

[0053] The positive electrode includes a positive electrode current collector, which includes an unloaded current collector or a current collector loaded with MnO2 active material.

[0054] The current collector is a three-dimensional high specific surface area metal or non-metal current collector;

[0055] The loading method is either pre-loading or in-situ electrodeposition loading;

[0056] The preload includes a pre-electrode deposition load or a load applied by blending binders and conductive agents or by drop coating.

[0057] The negative electrode includes a metallic negative electrode and a non-metallic negative electrode;

[0058] The metal anode includes one or more of zinc, copper, lead, tin, bismuth, cadmium, manganese, and indium;

[0059] The non-metallic negative electrode includes one or more organic compounds selected from hydrogen, sulfur, carbon, molybdenum trioxide, sodium titanium phosphate, hexamolybdenum octasulfide, quinones, phenazines, and imides.

[0060] In another aspect, the present invention also provides an electrolyte for an aqueous manganese-based battery as described above, and the application of the aqueous manganese-based battery as described above in the field of secondary energy storage.

[0061] This invention proposes an on-demand proton supply strategy for electrolytes and batteries. By utilizing the dissociation equilibrium of weak acids, it achieves "on-demand" proton supply, demonstrating unexpected technical effects, as detailed below:

[0062] 1. Synergistic effect enables precise proton control: Under static conditions, the low degree of dissociation of the weak acid effectively avoids the chemical dissolution of MnOOH and the reaction of Mn. 3+The generation of protons is achieved through the Le Chatelier principle, which causes the dissociation equilibrium of the weak acid to shift in the positive direction during discharge. Simultaneously, the electric field lowers the dissociation energy barrier of the weak acid at the electrode interface (molecular polarization theory). These two effects work synergistically to ensure precise and timely proton replenishment, meeting the demands of electrochemical dissolution. This dynamic and adaptive proton supply method is difficult to achieve with traditional strong acids or buffer solutions.

[0063] 2. Significantly Improved Dissolution Efficiency and Cycle Life: Through this on-demand supply, the present invention not only effectively suppresses the formation of "dead manganese" but also achieves near-complete electrochemical dissolution of MnO2. Experimental data from specific embodiments demonstrate that the Zn / / MnO2 full cell using a proton valve electrolyte achieves near-complete electrochemical dissolution at 0.5 mA cm⁻¹. -2 At low current densities, the cumulative discharge time exceeds 2650 hours (over 165 days of cycling), far surpassing traditional acidic electrolyte systems. This significant improvement in lifespan, especially while ensuring high manganese utilization, is something that existing technologies could not have predicted.

[0064] 3. Universality: This strategy is not only effective in the Zn / / MnO2 system, but also shows superiority in MoO3 / / MnO2 full cells with higher proton requirements.

[0065] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0066] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0067] Figure 1a The results of the chemical dissolution of quartz crystals by the electrolytes of Example 1 and Comparative Example 1 under static conditions are shown in the microbalance test. The inset shows the dissolution rate of Example 1 and Comparative Example 1 in different electrolytes.

[0068] Figure 1b These are optical photographs of the chemical dissolution and standing experiments of the electrolytes in Example 1 and Comparative Example 1.

[0069] Figure 2 This is a comparison of the in-situ Raman spectra of the electrolytes in Example 1 and Comparative Example 1.

[0070] Figure 3 This is a discharge curve of the three-electrode system assembled with electrolytes from Example 1 and Comparative Example 2 at the 10th cycle.

[0071] Figure 4 These are SEM images of the positive electrode of the three-electrode system assembled with electrolytes from Example 1 and Comparative Example 1 after cycling.

[0072] Figure 5 The full cells assembled with the electrolytes of Example 1 and Comparative Example 1 were tested at 0.5 mA / cm². -2 Cycle life curves tested at current density, with the inset showing the constant current discharge curve for the 100th cycle.

[0073] Figure 6 Another full cell assembled with the electrolytes of Example 1 and Comparative Example 1 was tested at 0.5 mA / cm². -2 Cycle life diagram tested at current density. Detailed Implementation

[0074] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0075] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0076] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0077] In a first aspect, the present invention provides an electrolyte for an aqueous manganese-based battery that enables on-demand proton supply. According to an embodiment of the invention, the electrolyte comprises:

[0078] The electrolyte, a manganese salt, is used to provide Mn. 2+ It supports MnO2 deposition / dissolution reactions;

[0079] The weak acid is used to regulate the dynamic release of protons at the positive electrode / electrolyte interface to achieve on-demand supply of protons at the positive electrode / electrolyte interface; that is, it acts as a "proton valve" to regulate the dynamic release of protons.

[0080] And the solvent, which is deionized water, to ensure the ionic conductivity and stability of the electrolyte.

[0081] The pH range of the above electrolyte is 2.0-3.5.

[0082] During the charging and discharging process of the battery, the electrolyte can provide protons to the positive electrode / electrolyte interface on demand, promoting the efficient and reversible deposition and dissolution reaction of manganese dioxide, the positive electrode active material.

[0083] According to some embodiments of the present invention, the pH range of the electrolyte can be 2.0-3.5, that is, the pH range can be any value between 2.0 and 3.5, for example, specifically 2.0, 2.2, 2.3, 2.4, 2.5, 2.7, 2.9, 3.0, 3.1, 3.2, 3.4, 3.5, etc., or a range composed of any of the above values.

[0084] According to some embodiments of the present invention, the pH range of the electrolyte is preferably 2.1-2.8. That is, the preferred pH range can be any value between 2.1 and 2.8, such as 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, etc., or a range composed of any of the above values.

[0085] According to some embodiments of the present invention, the pH range of the electrolyte is preferably 2.2-2.4. That is, the preferred pH range can be any value between 2.2 and 2.4, such as 2.2, 2.3, 2.4, etc., or a range composed of any of the above values.

[0086] In existing technologies, the main technical solutions to address the poor reversibility of MnO2 dissolution and the problem of "dead manganese" in aqueous manganese-based batteries include:

[0087] 1. Strongly acidic electrolytes: Strongly acidic electrolytes (e.g., pH ≤ 1) can be constructed by adding high concentrations of HCl or H₂SO₄ to an aqueous solution containing manganese salts. While these electrolytes can provide sufficient protons, as mentioned earlier, excessive protons can easily trigger the rapid chemical dissolution of MnOOH and the degradation of Mn. 3+ Disproportionation leads to loss of active material and decrease in coulombic efficiency, and is highly corrosive to current collectors and battery components.

[0088] 2. Near-neutral or weakly acidic electrolytes: such as near-neutral electrolytes using pH buffer systems (e.g., pH ~ 6) and weakly acidic electrolytes using only MnSO4 solution or with the addition of a small amount of acid (e.g., pH ≥ 4). These systems can largely avoid the use of MnSO4. 3 + While MnO2 can be generated, there is often a problem that the proton supply capacity and response speed may not be able to accurately match the dynamic demand for electrochemical dissolution of MnO2. This often results in insufficient proton supply, leading to incomplete dissolution of MnO2, rapid capacity decay, and the gradual accumulation of "dead manganese" during cycling.

[0089] Through extensive and continuous inventive work by the applicant, this invention controls the pH within the aforementioned range, fully utilizing the dynamic dissociation equilibrium of a specific weak acid at the electrode / electrolyte interface (co-regulated by Le Chatelier's principle and molecular polarization effect) to achieve on-demand proton supply at the electrode / electrolyte interface. In a specific pH environment, the specific weak acid acts like a "proton valve," effectively inhibiting chemical dissolution when excessive proton supply is not needed, while providing sufficient protons for complete electrochemical dissolution when required. Through precise on-demand proton supply, this invention significantly reduces the formation of "dead manganese," thereby overcoming the key development bottlenecks of short cycle life and poor reversibility in aqueous manganese-based batteries.

[0090] Specifically, when the pH is 2.0-3.5, preferably 2.1-2.8, and most preferably 2.2-2.4, it ensures that a specific weak acid (such as acrylic acid, pKa≈4.25) is in a partially dissociated state, with a moderate proton concentration, which satisfies the requirements for the electrochemical dissolution of MnO2 (MnO2 + 4H+). + +2e - →Mn 2+ +2H2O), while avoiding the chemical dissolution of MnOOH caused by excessive protons (MnOOH + 3H2O). + →Mn 3+ The proton concentration is high at pH < 2.0, which can lead to excessive chemical dissolution of MnOOH, exacerbating the problem of "dead manganese," causing loss of active substances, and reducing cycle life. At pH > 3.5, the proton concentration is insufficient, which, while effectively inhibiting excessive chemical dissolution of MnOOH, also limits the electrochemical dissolution of MnOOH (MnOOH + 3H₂O). + +e - The reaction Mn2+ + 2H2O leads to decreased dissolution efficiency and capacity decay. The pH range of 2.2–2.4 falls within the critical point range balancing electrochemical and chemical dissolution, where the MnO2 conversion efficiency is optimal.

[0091] According to some embodiments of the present invention, a specific weak acid refers to a weak acid with a pKa range of 3.0-6.0. That is, the pKa range of a weak acid can be any value between 3 and 6, for example, specifically 3, 3.5, 4, 4.5, 5, 5.5, 6, etc., or a range composed of any of the above values.

[0092] According to some embodiments of the present invention, the preferred range of pKa for a weak acid is 3.5-5.5. That is, the preferred range of pKa for a weak acid can be any value between 3.5 and 5.5, such as 3.5, 3.6, 3.8, 4, 4.2, 4.5, 5, 5.5, etc., or a range composed of any of the above values.

[0093] According to some embodiments of the present invention, the optimal range of pKa for a weak acid is 3.8-5.0. That is, the optimal range of pKa for a weak acid can be any value between 3.8 and 5.0, such as 3.8, 4, 4.2, 4.4, 4.5, 4.6, 4.8, 5, etc., or a range composed of any of the above values.

[0094] Considering that current aqueous manganese-based batteries based on MnO2 deposition / dissolution mechanisms suffer from incomplete dissolution reactions due to improper proton supply (too much or too little), resulting in the formation of Mn(III) intermediates and disproportionation to form "dead manganese," making it difficult to achieve highly reversible electrochemical reactions, the key to this invention lies in the design and use of a proton valve, that is, utilizing the dissociation equilibrium of a specific weak acid (similar to a weak acid with a suitable pKa value, such as acrylic acid) under a specific pH environment. It can suppress the excessive release of protons during standing to avoid the chemical dissolution of MnOOH and Mn 3+ The disproportionation of MnO2 occurs during the discharge process (MnO2 dissolution). Furthermore, based on the proton consumption caused by the electrochemical reaction, and through the synergistic effect of Le Chatelier's principle and the molecular polarization effect under the interfacial electric field, protons are supplied "on demand" and precisely, thereby promoting the complete electrochemical dissolution of MnO2 into Mn. 2+ This inhibits the formation of "dead manganese" and achieves efficient reversible dissolution of MnO2 through a synergistic effect, ultimately realizing a high-performance, long-life aqueous manganese-based battery based on the MnO2 deposition / dissolution mechanism.

[0095] Specifically, when a weak acid with a pKa of 3-6, preferably 3.5-5.5, and most preferably 3.8-5.0 is selected, the proton valve mechanism is established: through the dissociation equilibrium of the weak acid. Achieving on-demand proton supply differs from the static high proton concentration achieved by adding excessive strong acid to the electrolyte, thus avoiding the chemical dissolution of MnOOH. It also differs from near-neutral electrolytes with low proton concentrations, preventing MnO2 from failing to dissolve due to insufficient proton supply. The dissociation equilibrium of weak acids with pKa of 3-6 determines the dynamic nature of proton release, ensuring on-demand supply and avoiding oversupply or undersupply. Strong acids with pKa too low (pKa < 3) at the same pH have less proton reserves than weak acids. Protons in strong acids are usually completely dissociated, making it impossible to additionally dissociate protons to guarantee proton supply when a large amount of protons is needed for dissolution. Conversely, weak acids with pKa too high (pKa > 6), exceeding the range (such as boric acid), have difficulty dissociating protons. Although they have a large proton reserve, it cannot dissociate when protons are needed for dissolution, thus leading to an unreliable proton supply.

[0096] According to some embodiments of the present invention, in the electrolyte, the anion of the weak acid and the manganese ion of the manganese salt are in a non-coordinate relationship; the manganese salt is a non-coordinate anionic manganese salt.

[0097] The statement "The anion in a weak acid has a non-coordinate relationship with the manganese ion in a manganese salt" refers to the relationship between the weak acid anion and Mn in coordination chemistry. 2+ The coordination effect is very weak. That is, the weak acid anion reacts with Mn. 2+ The stability constant logK of the complex is very small, or the logK value cannot be found because there is no complexation relationship.

[0098] "Noncoordinate anionic manganese salt" refers to Mn in coordination chemistry. 2+ Manganese salts formed by weak ligands, specifically referring to the salt formed by the reaction of the anion in the salt with Mn. 2+ The coordination effect is weak. That is, the anion reacts with Mn. 2+ The stability constant logK of the complex is very small, or the logK value cannot be found because there is no complexation relationship.

[0099] According to some embodiments of the present invention, the stability constant logK of the complex between the anion of the weak acid and the manganese ion in the manganese salt is ≤9; the stability constant logK of the complex between the anion in the manganese salt and the manganese ion is ≤9. Further, the stability constant logK of the complex between the anion of the weak acid and the manganese ion in the manganese salt is ≤1; the stability constant logK of the complex between the anion in the manganese salt and the manganese ion is ≤1.

[0100] According to some embodiments of the present invention, the aforementioned weak acid includes one or more of acrylic acid (C3H4O2), formic acid (HCOOH), propionic acid (CH2CH3COOH), glycolic acid (CH2OHCOOH), and ascorbic acid (C6H8O6). That is, it can be a single weak acid or a combination of two or more weak acids. Specifically, it can be acrylic acid, formic acid, glycolic acid, acrylic acid + propionic acid, etc.

[0101] According to some embodiments of the present invention, the aforementioned weak acid is preferably acrylic acid or propionic acid, or a combination thereof. Acrylic acid (pKa≈4.25) has a suitable dissociation equilibrium, and its proton release rate can match the dissolution requirements of MnO2, and its -COO - Groups adsorb at the positive electrode interface, stabilizing the electrochemical interface.

[0102] In this invention, there is no specific range or optimal concentration for the weak acid; the optimal concentration of the weak acid varies for different pKas. Simply add a weak acid with a suitable pKa within the manganese salt concentration range described below to adjust the pH to the specified range. This ensures that the final electrolyte achieves a proper dissociation equilibrium, guaranteeing the on-demand supply of protons.

[0103] According to some embodiments of the present invention, the above-mentioned noncoordinate anionic manganese salt includes one or more of manganese sulfate (MnSO4), manganese chloride (MnCl2), manganese perchlorate (Mn(ClO4)2), manganese nitrate (Mn(NO3)2), and manganese bis(trifluoromethanesulfonate) (Mn(OTF)2).

[0104] In the electrolyte, anions strongly coordinated with manganese ions, regardless of whether they originate from the anion of a weak acid or from the dissolved manganese salt, such as manganese acetate (MnAc2) or Ac in acetic acid, are considered to be related to manganese ions. - , (Ac - With Mn 2+ The stability constant log K1 of the complex is as high as 9.84. The strong interaction between this anion and manganese ions leads to slow desolvation kinetics and difficult deposition of manganese ions, resulting in uneven deposition and the formation of low-valence, low-conductivity manganese-based compounds (non-target product MnO2). Under high loading, a large amount of "dead manganese" with electrical contact failure is generated. Deposition and dissolution are closely related, and the deposition quality directly affects the dissolution efficiency. In summary, MnO2, which has a high stability constant log K1 in coordination chemistry, should be selected. 2+ The manganese salt with a weak ligand anion or a weak acid, i.e., a non-coordinated manganese salt or a weak acid containing a non-coordinated weak acid anion. For example, if logK < 9, a non-coordinated manganese salt with logK < 1 is preferred, specifically SO42-. 2- Taking manganese sulfate, which is an anion, as an example, in this type of manganese salt, the anion reacts with Mn. 2+ The stability constant of divalent metal ion complexes is low, even negligible, indicating that anions do not affect deposition in this process, thus minimizing the influence of deposition products on the dissolution process.

[0105] According to some embodiments of the present invention, the concentration of the manganese salt in the electrolyte is 0.005-6.0M. That is, the concentration of the manganese salt can be any value between 0.005M and 6.0M, for example, specifically 0.005M, 0.01M, 0.1M, 1M, 1.5M, 2M, 2.5M, 3M, 4M, 5M, 6M, etc., or a range of any of the above values.

[0106] According to some embodiments of the present invention, the preferred concentration of the manganese salt in the electrolyte is 0.3-3.0M. That is, the concentration of the manganese salt can be any value between 0.3M and 2.0M, for example, specifically 0.3M, 0.4M, 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, etc., or a range of any of the above values.

[0107] According to some embodiments of the present invention, the preferred concentration of the manganese salt in the electrolyte is 0.5-2.0M. That is, the concentration of the manganese salt can be any value between 0.5M and 2.0M, for example, specifically 0.5M, 0.6M, 0.8M, 1M, 1.2M, 1.5M, 1.8M, 2M, etc., or a range of any of the above values.

[0108] When manganese salts are within the specific concentration range mentioned above, Mn 2+ The concentration balances the ionic conductivity of the electrolyte (approximately 10-20 mS / cm) and the MnO2 deposition efficiency in the battery. Since the active material of aqueous manganese-based batteries based on this mechanism is entirely derived from the electrolyte, the MnO2 areal loading is closely related to the manganese salt concentration. Too low a manganese salt concentration (<0.005 M) is insufficient to support high-capacity MnO2 deposition, limiting the development of high-load, high-energy-density batteries; while high manganese salt concentrations (>6.0 M) may lead to increased electrolyte viscosity and higher costs. Therefore, the manganese salt concentration needs to be within the aforementioned range to ensure sufficient MnO2 deposition efficiency. 2+ Sufficient and stable electrolyte, suitable for long-term cycling.

[0109] According to some embodiments of the present invention, the electrolyte further includes a second soluble electrolyte salt, the type of which depends on the type of negative electrode that matches the positive electrode of the manganese-based battery; for example, if an aqueous zinc-manganese battery is constructed, the added electrolyte salt should be a soluble zinc salt; if an aqueous copper-manganese battery is constructed, the added electrolyte salt should be a soluble copper salt.

[0110] According to some embodiments of the present invention, the concentration of the second soluble electrolyte salt is 0–3.0 M, preferably 0.3–2.0 M, and most preferably 0.5–2.0 M. That is, the concentration of the second soluble electrolyte salt can be any value between 0 M and 3.0 M, or between 0.3 M and 2.0 M, or between 0.5 M and 2.0 M. Specifically, it can be 0 M, 0.1 M, 0.6 M, 0.8 M, 1 M, 1.2 M, 1.5 M, 1.8 M, 2 M, 2.5 M, 2.8 M, 3 M, etc., or a range of any of the above values. It should be noted that when the concentration of the second soluble electrolyte salt is 0 M, it means that the second soluble electrolyte salt is not present in the electrolyte.

[0111] The addition of a specific concentration of the second soluble electrolyte salt is to ensure the stable operation of the aqueous manganese-based full battery. The type of the second soluble electrolyte salt depends on the type of negative electrode it is matched with. The concentration of the second soluble electrolyte salt can vary depending on the type of negative electrode it is matched with. For example, in a zinc-manganese battery, the addition of soluble zinc salt is to ensure sufficient Zn in the electrolyte. 2+ To ensure the electrochemical reaction required on the zinc negative electrode side, such as during charging, Zn... 2+It will deposit back onto the zinc anode surface, and the Zn anode will dissolve during discharge. The addition of Zn salt in the electrolyte is to ensure the ionic conductivity of the electrolyte and to ensure the occurrence of the reversible reaction solution at the anode.

[0112] According to some embodiments of the present invention, the electrolyte further includes optional additives. Optional additives include surfactants, redox media (not mandatory, concentration <0.01M), etc., which can be added according to actual needs.

[0113] In another aspect of the present invention, a method for preparing an electrolyte for an aqueous manganese-based battery that enables on-demand proton supply is provided.

[0114] According to some embodiments of the present invention, the preparation method includes: dissolving manganese salt in deionized water to form a manganese salt aqueous solution, adding one or more weak acids to the manganese salt aqueous solution, adjusting the final pH value of the solution to 2.0-3.5 using the weak acids, and stirring evenly to obtain the above-mentioned electrolyte.

[0115] It should be noted that the components of the electrolyte, as well as the types and concentrations of each component, have been described in detail. The characteristics and advantages described above for the electrolyte also apply to the preparation method of the electrolyte, and will not be repeated here.

[0116] The above method uses a weak acid with moderate proton supply capacity (pKa within the specified range), adjusts the pH range, and matches suitable manganese salt types and concentrations to construct a proton-on-demand electrolyte, dynamically controlling proton release. In existing technologies, at the same pH, strong acids are used for adjustment. Strong acids have less proton reserves than weak acids, and protons in strong acids are usually completely dissociated, making it impossible to additionally dissociate protons to ensure proton supply when a large number of protons are needed for dissolution. On the other hand, weak acids with excessively large pKa (such as boric acid) have difficulty dissociating protons. Although they have a large proton reserve, they cannot dissociate when protons are needed for MnO2 dissolution, thus leading to an unreliable proton supply. If only weak acid manganese salts like manganese acetate are used for pH adjustment, firstly, manganese acetate is a coordinated manganese salt, and the anion has a strong interaction force with manganese ions (logK1 is as high as 9.84), which leads to slow desolvation kinetics of manganese ions and difficulty in deposition. This results in uneven deposition and the formation of low-valence, low-conductivity manganese-based compounds (non-target product MnO2). Under high load, a large amount of "dead manganese" with electrical contact failure is generated. Secondly, manganese acetate is a weak acid-weak base salt, and its aqueous solution is neutral (pH≈7). It is impossible to achieve wide-range pH control by simply adjusting the salt concentration. If the pH needs to be adjusted to the acidic range, a large amount of acetic acid needs to be added. However, adding too much acetic acid introduces too many acetate ions, which prevents the formation of MnO2.

[0117] In another aspect, the present invention provides an aqueous manganese-based battery for achieving on-demand proton supply. The battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte is the aqueous manganese-based battery electrolyte described above.

[0118] According to an embodiment of the present invention, the battery includes the electrolyte described in the above embodiments or an electrolyte obtained by the method for preparing the electrolyte described in the above embodiments. It should be noted that the features and advantages described above for the electrolyte also apply to the battery, and will not be repeated here.

[0119] According to some embodiments of the present invention, the above-mentioned aqueous manganese-based battery, based on the deposition / dissolution mechanism of MnO2, is assembled from a current collector without load or a current collector loaded with MnO2 active material as the positive electrode, a suitable negative electrode (e.g., Zn, MoO3, etc.) and a separator.

[0120] According to some embodiments of the present invention, the positive electrode of the battery includes an unloaded current collector or a current collector loaded with MnO2 active material. "Unloaded current collector" refers to a current collector without any load and can be directly used as the positive electrode of the battery.

[0121] According to some embodiments of the present invention, the current collector is a three-dimensional high specific surface area metal or non-metal current collector, and the loading method is pre-loading or in-situ electrodeposition loading, wherein pre-loading includes pre-electrodeposition loading or loading by co-coating or drop-coating with binders and conductive agents. Specifically, the three-dimensional high specific surface area current collector can be carbon cloth, carbon paper, carbon felt, etc.

[0122] Compared with two-dimensional metal foils, current collectors with three-dimensional porous structures can provide a larger adhesion area and more reactive sites for the positive electrode manganese dioxide active material, thereby reducing the electron transport barrier between the manganese dioxide active material and the current collector, minimizing "dead manganese" caused by electrical contact failure, and providing a solution for the development of high-load, high-energy-density aqueous manganese-based batteries.

[0123] According to some embodiments of the present invention, the negative electrode of the battery includes a metallic negative electrode and a non-metallic negative electrode.

[0124] According to some embodiments of the present invention, the metal anode includes one or more of zinc (Zn), copper (Cu), lead (Pb), tin (Sn), bismuth (Bi), cadmium (Cr), manganese (Mn), and indium (In); the non-metallic anode includes one or more of hydrogen (H2), sulfur (S), carbon (C), molybdenum trioxide (MoO3), sodium titanium phosphate (NTP), hexamolybdenum octasulfide (Mo6S8), quinones, phenazines, and imides.

[0125] According to some embodiments of the present invention, the negative electrode of the battery is preferably Zn (surface In modified).

[0126] The core advantage of zinc (Zn) as a negative electrode material for aqueous manganese-based batteries lies in the perfect combination of its high theoretical capacity, low cost, excellent safety, and environmental friendliness. Zn has an 820mAh g... -1 The specific capacity and 5855mAh cm -3 Zinc has a high volumetric capacity; it is also abundant in the Earth's crust and costs only about $2–3 / kg, making it suitable for large-scale energy storage; furthermore, zinc is non-toxic and easily recyclable, matching the green characteristics of aqueous electrolytes and meeting the needs of sustainable development. However, zinc suffers from severe hydrogen evolution and corrosion problems in acidic electrolytes (such as pH 2.2–2.5), limiting its compatibility with manganese dioxide cathodes based on deposition / dissolution mechanisms. Therefore, modifying the Zn surface with In, which has a high hydrogen evolution overpotential, can greatly solve the incompatibility problem between Zn anodes and acidic electrolytes. Ultimately, the In-modified Zn anode can achieve stable cycling in a proton-on-demand electrolyte system, making it an ideal choice for anodes in aqueous manganese-based batteries.

[0127] According to some embodiments of the present invention, the battery separator includes glass fiber, nonwoven fabric, cellulose, etc. It needs to have good electrolyte wettability and mechanical strength.

[0128] Another aspect of the present invention provides a method for applying an electrolyte that enables on-demand proton supply to an aqueous manganese-based battery.

[0129] According to some embodiments of the present invention, the specific steps for applying the above-mentioned electrolyte to an aqueous manganese-based battery are as follows:

[0130] S1: Electrolyte preparation;

[0131] S2: Selection of negative electrode and separator and battery assembly.

[0132] It should be noted that the electrolyte preparation method is as described above, the negative electrode and separator selection is as described above, and the features and advantages described above for the electrolyte and battery also apply here.

[0133] According to some embodiments of the present invention, the battery is assembled using a self-made acrylic mold. The mold uses an acrylic sheet as a support and consists of carbon cloth (positive electrode current collector), negative electrode (zinc foil), sealing sheet, and stainless steel tabs. The battery assembly steps are as follows: using insulated tweezers, assemble the battery in the following order: acrylic sheet, stainless steel tabs, negative electrode, sealing gasket, acrylic sheet, sealing gasket, carbon cloth, stainless steel tabs, and acrylic sheet. After assembly, tighten the screws to ensure a tight seal.

[0134] Another aspect of the present invention provides an electrolyte for an aqueous manganese-based battery that enables on-demand proton supply as described above, and the application of the aqueous manganese-based battery as described above in the field of secondary energy storage.

[0135] The on-demand proton supply in this invention benefits from the weak acid dissociation equilibrium regulation (pKa 3-6, preferably acrylic acid) synergistically influenced by Le Chatelier's principle and molecular polarization effect. Specifically, it involves suppressing excessive proton release during static standing to avoid the chemical dissolution of MnOOH and the release of Mn. 3+ The disproportionation of MnO2 occurs during the discharge process (MnO2 dissolution). Furthermore, based on the proton consumption caused by the electrochemical reaction, and through the synergistic effect of Le Chatelier's principle and the molecular polarization effect under the interfacial electric field, protons are supplied "on demand" and precisely, thereby promoting the complete electrochemical dissolution of MnO2 into Mn. 2+ This inhibits the formation of "dead manganese" and ultimately achieves high-performance, long-life aqueous manganese-based batteries based on deposition / dissolution mechanisms.

[0136] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0137] Example 1

[0138] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and acrylic acid, with the pH adjusted to 2.3. The manganese sulfate concentration is 0.5 mol / L, and the pKa of the acrylic acid is 4.26. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molality of 0.5 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and bring the volume to a final consistency. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0139] Example 2

[0140] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and formic acid, with the pH adjusted to 2.3. The manganese sulfate concentration is 0.5 mol / L, and the formic acid pKa is 3.75. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add formic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and bring the volume to a final level. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0141] Example 3

[0142] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and propionic acid, with the pH adjusted to 3.5. The manganese sulfate concentration is 0.5 mol / L, and the pKa of the propionic acid is 4.87. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add propionic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 3.5 and bring the volume to a final consistency. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0143] Example 4

[0144] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and glycolic acid, with the pH adjusted to 2.0. The manganese sulfate concentration is 0.5 mol / L, and the pKa of the glycolic acid is 3.83. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add glycolic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.0 and bring the volume to a final consistency. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0145] Example 5

[0146] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and acrylic acid, with the pH adjusted to 2.3. The manganese sulfate concentration is 1.0 mol / L, and the pKa of the acrylic acid is 4.26. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a concentration of 1.0 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and bring the volume to a final level. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0147] Example 6

[0148] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese perchlorate and acrylic acid, with the pH adjusted to 2.3. The concentration of manganese perchlorate is 0.5 mol / L, and the pKa of acrylic acid is 4.26. The preparation method is as follows: Weigh the mass of manganese perchlorate hexahydrate at a volumetric molar concentration of 0.5 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and bring the volume to a final consistency. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0149] Example 7

[0150] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate, acrylic acid, and propionic acid, with the pH adjusted to 2.3. The concentration of manganese sulfate is 0.5 mol / L, the pKa of acrylic acid is 4.26, and the pKa of propionic acid is 4.76. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric mol / L concentration of 0.5 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes until completely dissolved to form a clear solution. Add a mixed solution of acrylic acid and propionic acid (molar ratio 1:1) dropwise to this solution, while simultaneously monitoring the pH value using a pH meter. Adjust the pH to 2.3 and complete the volume adjustment. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0151] Example 8

[0152] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate + manganese perchlorate + acrylic acid, with the pH adjusted to 2.3. The concentrations of manganese sulfate and manganese perchlorate are both 0.25 mol / L, and the total Mn content in the electrolyte is [not specified]. 2+ The concentration is 0.5 mol / L, and the pKa of acrylic acid is 4.26. The preparation method is as follows: Weigh out manganese sulfate monohydrate and manganese perchlorate hexahydrate at a volume mol / L concentration of 0.25 mol / L, and add them to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes until completely dissolved to form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and then bring the volume to a final level. Stir until homogeneous to obtain the proton-on-demand electrolyte for this example.

[0153] Example 9

[0154] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and acrylic acid, with the pH adjusted to 2.3. The manganese sulfate concentration is 2 mol / L, and the pKa of the acrylic acid is 4.26. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molality of 2 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and bring the volume to a final consistency. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0155] Example 10

[0156] This embodiment provides a proton-on-demand electrolyte, specifically composed of manganese sulfate and acrylic acid, with the pH adjusted to 2.3. The manganese sulfate concentration is 4 mol / L, and the pKa of the acrylic acid is 4.26. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 4 mol / L, and add it to an appropriate amount of deionized water in a beaker. Stir and mix for 20 minutes to completely dissolve and form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter. Adjust the pH to 2.3 and bring the volume to a final consistency. Stir until homogeneous to obtain the proton-on-demand electrolyte of this example.

[0157] Comparative Example 1

[0158] This comparative example provides a non-proton-on-demand electrolyte as a reference for comparison with a proton-on-demand electrolyte. Its specific composition is manganese sulfate + hydrochloric acid, with the pH adjusted to 2.3. The concentration of manganese sulfate is 0.5 mol / L, and the pKa of hydrochloric acid is -6.2. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add hydrochloric acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 2.3, and then bring the volume to a final consistency. Stir until homogeneous to obtain the non-proton-on-demand electrolyte of this example.

[0159] Comparative Example 2

[0160] This comparative example provides a non-proton-on-demand electrolyte as a reference for comparison with a proton-on-demand electrolyte. Its specific composition is manganese sulfate + perchloric acid, with the pH adjusted to 2.3. The concentration of manganese sulfate is 0.5 mol / L, and the pKa of perchloric acid is -1.6. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add perchloric acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 2.3, and then bring the volume to a final consistency. Stir until homogeneous to obtain the non-proton-on-demand electrolyte of this example.

[0161] Comparative Example 3

[0162] This comparative example provides a non-proton-on-demand electrolyte as a reference for comparison with a proton-on-demand electrolyte. Its specific composition is manganese sulfate + sulfuric acid, with the pH adjusted to 2.3. The concentration of manganese sulfate is 0.5 mol / L, and the pKa1 of sulfuric acid is -1.99. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add sulfuric acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 2.3, and then bring the volume to a final consistency. Stir until homogeneous to obtain the non-proton-on-demand electrolyte of this example.

[0163] Comparative Example 4

[0164] This comparative example provides a non-proton-on-demand electrolyte as a reference for comparison with a proton-on-demand electrolyte. Its specific composition is manganese sulfate + boric acid, with the pH adjusted to 4. The concentration of manganese sulfate is 0.5 mol / L, and the pKa of boric acid is 9.24. Adding boric acid with a pKa of 9.24 limits its proton dissociation ability, making it unable to supply sufficient protons. Even if the amount of boric acid added reaches saturation (the electrolyte cannot dissolve more boric acid), the pH is still difficult to reach below 3.5. Therefore, a pH of 4 was chosen in this comparative example. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add boric acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 4, and then bring the volume to a final consistency. Stir until homogeneous to obtain the non-proton-on-demand electrolyte of this example.

[0165] Comparative Example 5

[0166] This comparative example provides a non-proton-on-demand electrolyte as a reference for comparison with a proton-on-demand electrolyte. Its specific composition is manganese sulfate + hydrochloric acid, pH adjusted to 1, wherein the concentration of manganese sulfate is 0.5 mol / L, and the pKa1 of hydrochloric acid is -6.2. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add hydrochloric acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 1, and then bring the volume to a final consistency. Stir until homogeneous to obtain the non-proton-on-demand electrolyte of this example.

[0167] Comparative Example 6

[0168] This comparative example provides an electrolyte prepared with non-proton-on-demand non-coordinated anions as a reference for comparison with proton-on-demand electrolytes. Its specific composition is manganese sulfate, with a concentration of 0.5 mol / L and an electrolyte pH of 4.3. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate according to a volumetric molar concentration of 0.5 mol / L, and add it to an appropriate amount of water in a beaker. Stir and mix for 20 minutes until completely dissolved to form a clear solution, thus obtaining the non-proton-on-demand electrolyte of this example.

[0169] Comparative Example 7

[0170] This comparative example provides a Mn 2+ An electrolyte with a strongly coordinating anion in its solvated structure was used as a reference for comparison with an electrolyte that supplies uncoordinated protons on demand. Its specific composition is manganese acetate + acetic acid, with the pH adjusted to 4.3, and the concentration of manganese acetate is 0.5 mol / L. The preparation method is as follows: Weigh the mass of manganese acetate tetrahydrate according to a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add acetic acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 4.3, and then bring the volume to a final consistency. Stir until homogeneous to obtain the strongly coordinating anion electrolyte of this example.

[0171] Comparative Example 8

[0172] This comparative example provides a Mn 2+ An electrolyte with a strongly coordinating anion in its solvated structure was used as a reference for comparison with an electrolyte that supplies uncoordinated protons on demand. Its specific composition is manganese acetate, pH 6.9, with a manganese acetate concentration of 0.5 mol / L. The preparation method is as follows: Weigh the mass of manganese acetate tetrahydrate according to a volumetric molar concentration of 0.5 mol / L, and add it to an appropriate amount of water in a beaker. Stir and mix for 20 min to completely dissolve and form a clear solution. After thorough stirring, the strongly coordinating anion electrolyte of this example is obtained.

[0173] Comparative Example 9

[0174] This comparative example provides a Mn 2+ An electrolyte with a strongly coordinating anion in its solvated structure was used as a reference for comparison with an electrolyte that supplies uncoordinated protons on demand. Its specific composition is manganese acetate + acetic acid, with the pH adjusted to 2.3, and the concentration of manganese acetate is 0.5 mol / L. The preparation method is as follows: Weigh the mass of manganese acetate tetrahydrate according to a volumetric molar concentration of 0.5 mol / L, add it to an appropriate amount of water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add acetic acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 2.3, and then bring the volume to a final consistency. Stir until homogeneous to obtain the strongly coordinating anion electrolyte of this example.

[0175] Comparative Example 10

[0176] This comparative example provides a proton-on-demand electrolyte with an extremely low manganese salt concentration. Its specific composition is manganese sulfate + acrylic acid, with the pH adjusted to 2.3. The manganese sulfate concentration is 0.0001 mol / L, and the pKa of the acrylic acid is 4.26. The preparation method is as follows: Weigh the mass of manganese sulfate monohydrate at a volumetric molality of 0.0001 mol / L, add it to an appropriate amount of deionized water in a beaker, and stir for 20 minutes to completely dissolve and form a clear solution. Add acrylic acid dropwise to this solution while monitoring the pH value using a pH meter, adjust the pH to 2.3, and then bring the volume to a final level. Stir until homogeneous to obtain the extremely low manganese salt concentration proton-on-demand electrolyte of this example.

[0177] The experimental conditions for the above embodiments and comparative examples are summarized in Table 1 below.

[0178] Table 1

[0179]

[0180]

[0181] Application Example 1

[0182] Chemical dissolution experiments were conducted using the electrolytes prepared in Examples 1-5 and Comparative Examples 1-3 to verify the inhibitory effect of proton-on-demand supply of electrolyte on simple chemical dissolution.

[0183] The specific experimental procedure was as follows: MnOOH was pre-loaded onto a quartz crystal wafer, and its chemical dissolution rate was monitored by tracking the mass change of MnOOH during immersion in the electrolyte using a quartz crystal microbalance. The synthesis method for MnOOH involved dissolving 2 mmol of potassium permanganate (KMnO4) and 4 mL of polyethylene glycol (PEG, molecular weight 600) in 60 mL of deionized water at room temperature for 1 hour. The solution was then transferred to a 100 mL stainless steel high-pressure reactor and subjected to a hydrothermal reaction at 120 °C for 2 hours. After cooling to room temperature, the product was washed three times each with deionized water and anhydrous ethanol in a centrifuge, and then dried in a vacuum drying oven at 60 °C for 12 hours to obtain a powder sample. The chemical dissolution experiment involved placing the synthesized MnOOH powder in 20 mL of electrolyte and allowing it to stand for 48 hours, observing any changes.

[0184] Figure 1a and Figure 1b The results of chemical dissolution experiments using the electrolytes of Example 1 and Comparative Example 1 under static conditions are presented. Figure 1aThe results of the microbalance test on the chemical dissolution of quartz crystals under static conditions are shown in the inset, with the dissolution rate of MnOOH in different electrolytes displayed. Figure 1b An optical photograph of a chemical dissolution and settling experiment.

[0185] The chemical dissolution rate of MnOOH in the two electrolytes was evaluated under static conditions using a quartz crystal microbalance (QCM). Figure 1a As shown in the figure, the results indicate that in both electrolytes, the mass loss of MnOOH within 300 seconds is less than 2%, corresponding to a dissolution rate of less than 1 ng / s. -1 MnOOH powder was placed in two different electrolytes and allowed to stand for 48 hours; no changes were observed. (Specific details are as follows...) Figure 1b As shown in the figure, the results of the above static experiment confirm that MnOOH does not chemically dissolve in the electrolyte at pH 2.3. This verifies that the above electrolyte can effectively inhibit chemical dissolution, laying the foundation for on-demand proton supply.

[0186] The experimental data and results of chemical dissolution experiments using electrolytes from other embodiments and comparative examples are similar to those described above. This indicates that when the electrolyte pH ≥ 2, the free protons in the electrolyte are insufficient to promote excessive chemical dissolution of MnOOH, laying an important foundation for achieving complete electrochemical dissolution and realizing on-demand proton supply.

[0187] Application Example 2

[0188] In-situ Raman monitoring was performed using the electrolytes prepared in Examples 1-5 and Comparative Examples 1-3 to study the MnO2 deposition / dissolution process.

[0189] The specific experimental and testing procedures were as follows: Electrochemical in-situ Raman spectroscopy was performed using a LabRAM Odyssey Nano Raman spectrometer from HORIBA (France), employing a 532nm laser. Specifically, it was conducted in an electrochemical in-situ Raman cell. The electrochemical in-situ Raman spectroscopy in this paper was performed in a three-electrode system, with a working electrode (carbon cloth), an auxiliary electrode (carbon cloth), and a reference electrode (silver / silver chloride electrode) installed. Electrolytes from the examples and comparative examples were added to the intermediate chamber of the electrochemical in-situ Raman cell before focusing and testing. The constant current charge-discharge program was controlled by an Ivy electrochemical workstation from the Netherlands.

[0190] Figure 2 This study demonstrates the deposition and dissolution of MnO2 in a three-electrode system using Example 1 and Comparative Example 1, with simultaneous in-situ Raman spectroscopy monitoring and comparison. The results show that the characteristic Raman peak of MnO2 (approximately 450-650 cm⁻¹) can be observed in both electrolytes. -1The peak appears during deposition and disappears during dissolution. However, during discharge, the disappearance of the MnO2 peak and the reappearance of the substrate peak in Example 1 are both earlier than in Comparative Example 1. The earlier disappearance of the MnO2 peak indicates that MnO2 dissolves faster in Example 1, and the dissolution efficiency of MnO2 is higher in the same time. The appearance of the substrate peak is because MnO2 is loaded on the substrate. If MnO2 dissolves completely earlier, the substrate will be exposed earlier. Both of these points indicate that, compared to Comparative Example 1, MnO2 can dissolve more efficiently in Example 1 under proton-on-demand supply. This shows that the proton valve in the proton-on-demand supply electrolyte can supply protons on demand, promoting more efficient and complete electrochemical dissolution of MnO2.

[0191] In-situ Raman spectroscopy monitoring of MnO2 deposition / dissolution was performed using electrolytes from other examples and comparative examples, and the experimental data and results were similar to those described above. This indicates that the electrolyte can supply protons as needed, promoting the complete electrochemical dissolution of manganese dioxide.

[0192] Application Example 3

[0193] To evaluate the reversibility of the manganese dioxide deposition and dissolution process in each electrolyte (i.e., whether the manganese dioxide deposition is completely electrochemically dissolved), and to further verify that the electrolyte of this invention can achieve precise proton control and reduce the generation of "dead manganese," the electrolytes prepared in Examples 1-11 and Comparative Examples 1-11 were subjected to electrochemical quartz crystal microbalance tests during the dissolution process to measure their mass-charge conversion efficiency.

[0194] Mass-charge conversion efficiency (MCE) refers to the ratio of the actual mass consumed during discharge to the theoretical mass consumed corresponding to the charge consumed by the electrochemical dissolution of MnO2. This takes into account the electrochemical dissolution of MnO2 (MnO2→Mn... 2+ The electrochemical dissolution of MnO2 is a process involving both charge transfer and changes in active mass. Mechanism of electrochemical reaction (MCE) can more effectively reflect whether the electrochemical dissolution reaction of MnO2 actually occurs. Therefore, MCE can be used to evaluate the actual dissolution efficiency of MnO2. Specifically, a 100% MCE indicates that all the charge consumed during the discharge process is used for the electrochemical dissolution of MnO2, corresponding to the ideal situation of complete electrochemical dissolution of MnO2, where the theoretical mass change perfectly matches the change in the two-electron dissolution reaction. However, if only the MnO2 conversion reaction or incomplete dissolution reaction occurs, the mass change does not match the charge transfer in the electrochemical dissolution of MnO2, and the MCE value will be significantly lower. Therefore, MCE can clearly distinguish different reaction pathways and achieve the assessment of the actual dissolution efficiency of MnO2.

[0195] Because the dissolution reaction of manganese dioxide affects protons (H) +Manganese dioxide is highly concentration-sensitive; it can only undergo complete electrochemical dissolution when the interfacial proton concentration matches the electron supply rate. If the interfacial proton concentration is too high in a strongly acidic electrolyte, it will accelerate the chemical dissolution of the intermediate product MnOOH, generating a large amount of unstable Mn. 3+ These Mn ions 3+ The electrolyte is prone to disproportionation reactions, generating electrochemically inert "dead manganese," leading to loss of active material and poor cycle performance. Conversely, if the proton concentration in the weakly acidic or near-neutral electrolyte is insufficient, the complete electrochemical dissolution reaction of MnO2 cannot be effectively driven, causing the reaction to stagnate at the stage of generating the intermediate product MnOOH, resulting in incomplete dissolution and similarly causing capacity decay and accumulation of "dead manganese." This embodiment, by testing its mass-charge conversion efficiency, can effectively evaluate the reversibility of the manganese dioxide deposition and dissolution process of each electrolyte, i.e., the amount of "dead lithium" generated, thereby verifying the effective and precise control of protons by the electrolyte of this invention.

[0196] The specific testing process is as follows: The charge and mass changes of MnO2 during deposition and dissolution in different electrolytes are monitored using an electrochemical quartz crystal microbalance (EQCM). The test results are analyzed and fitted to obtain the MCE in different electrolytes. In-situ EQCM tests are all conducted in a three-electrode system, using a gold-plated quartz crystal chip as the working electrode, carbon cloth as the auxiliary electrode, and a silver / silver chloride electrode (saturated potassium chloride solution) as the reference electrode. The electrolyte used is the one required for the corresponding test, and the electrolyte volume is 460 μL. During the test, WinQCM software is used to collect information on frequency (f) and resonant resistance (R), and an electrochemical workstation from either the Dutch company Ivy or Chenhua is used to apply electrochemical signals and collect electrochemical data.

[0197] Table 2 shows the test results of mass-charge conversion efficiency for different electrolytes.

[0198] A comparison of Examples 1-5 with Comparative Examples 1 and 2 shows that, at pH = 2.3, the MCE of the proton-on-demand electrolyte with the proton valve supplying protons on demand can generally reach over 90%, which is significantly higher than the ~60% in the non-proton-on-demand electrolyte. A comparison of Example 1 with Comparative Examples 4 and 5 shows that when the pH is not in the optimal pH range of 2.0-3.5 and the pKa is not in the effective range of 3.0-6.0, the MCE is significantly reduced and the actual dissolution efficiency of MnO2 is significantly decreased.

[0199] Compared with Comparative Example 9, even at the optimal pH range (pH = 2.3), the strongly coordinated acetate ions in manganese salts, compared with non-coordinated sulfate ions, made MnO2 deposition difficult, resulting in poor deposition quality, subsequent dissolution difficulties, and a significant reduction in MCE.

[0200] Table 2

[0201]

[0202]

[0203] Application Example 4

[0204] Constant current charge-discharge tests were conducted using the electrolytes prepared in Example 1 and Comparative Example 1, and the positive electrode after cycling was characterized by scanning electron microscopy (SEM) to investigate whether the above electrolytes can achieve on-demand supply of protons during the dissolution process of manganese dioxide.

[0205] The specific experimental testing procedure was as follows: Constant current charge-discharge tests were conducted in a three-electrode electrochemical cell. After cycling, the electrodes were removed, cleaned, and characterized using a scanning electron microscope. The three-electrode system used in this test mainly consisted of carbon cloth and an auxiliary electrode, with a silver / silver chloride electrode (saturated potassium chloride solution) as the reference electrode. The electrolyte was the specific electrolyte required for the test, and the electrolyte volume was 10 mL. Discharge tests were conducted using a Blue Battery testing system, with a discharge current density of 0.5 mA cm⁻¹. -2 .

[0206] Figure 3 The discharge curves of the three-electrode systems assembled using the electrolytes of Example 1 and Comparative Example 1 at the 10th cycle are shown. The results show that the discharge plateau of Example 1 is longer than that of Comparative Example 1, and the discharge capacity decay of Comparative Example 1 is significantly lower, indicating that the MnO2 in the non-proton-on-demand electrolyte is not completely dissolved.

[0207] Furthermore, Figure 4 The SEM images of the positive electrode after cycling of the three-electrode assembly of the electrolytes of Example 1 and Comparative Example 1 are shown. The results show that a large amount of undissolved "dead manganese" residue was observed on the carbon cloth of the positive electrode in Comparative Example 1, while the surface of the carbon cloth in Example 1 was relatively clean, which further confirms that Example 1 can promote the complete dissolution of MnO2.

[0208] Following the above testing procedure, the electrolytes configured in the remaining comparative examples and embodiments were subjected to constant current charge-discharge tests, and the positive electrode sheets after cycling were characterized by scanning electron microscopy (SEM). The characterization results are shown in Table 3. Table 3 shows the SEM images of the positive electrodes after cycling with different electrolytes in a three-electrode system.

[0209] Table 3

[0210]

[0211] Application Example 5

[0212] Based on the electrolytes prepared in Example 1 and Comparative Example 1, 1M ZnSO4 was added to each to assemble a Zn|In / / MnO2 aqueous manganese-based full cell. The amount of electrolyte added to the full cell, based on the positive electrode area, was 1.0 mL / cm². 2 After assembly, the charge / discharge and cycle life of the full battery were tested.

[0213] The specific assembly and testing process is as follows: The battery is assembled using a self-made acrylic mold. The mold uses an acrylic sheet as a support and consists of carbon cloth (positive electrode current collector), negative electrode (zinc foil), sealing sheet, and stainless steel tabs. The specific assembly steps are as follows: Using insulated tweezers, assemble the battery in the following order: acrylic sheet, stainless steel tabs, negative electrode, sealing gasket, acrylic sheet, separator, sealing gasket, carbon cloth, stainless steel tabs, and acrylic sheet. After assembly, tighten the screws to ensure a seal, and use a dropper to add 1 mL of carbon cloth relative to the positive electrode area. -2 The electrolyte. Constant current charge-discharge testing was performed using the Blue Battery testing system.

[0214] Figure 5 The Zn|In / / MnO2 full cells configured using the electrolytes of Example 1 and Comparative Example 1 with the addition of ZnSO4 are demonstrated at 0.5 mA / cm². -2 The cycle life curve tested at current density, with the inset showing the 100th galvanostatic discharge curve, shows that the discharge plateau length of Example 1 is significantly longer than that of Comparative Example 1, and its final discharge capacity is also higher. The results show that the full cell using Example 1 exhibits an ultra-long cycle life, with stable cycles exceeding 2650 times and a cumulative discharge time exceeding 165 days, while the full cell of Comparative Example 1 fails rapidly after approximately 150 cycles. This is because the on-demand proton supply in Example 1 promotes the complete electrochemical dissolution of manganese dioxide, resulting in no dead manganese accumulation and ultimately achieving stable cycling of a highly reversible, long-life aqueous manganese-based battery. In contrast, the non-proton-supply electrolyte in the Comparative Example, due to insufficient proton supply, has a large amount of "dead manganese" residue after 150 cycles, greatly affecting the battery's reversibility and cycle life, ultimately leading to rapid failure.

[0215] Application Example 6

[0216] MoO3 / / MnO2 full cells were assembled using the electrolytes prepared in Example 1 and Comparative Example 1. The amount of electrolyte added to the full cell, based on the positive electrode area, was 1.0 mL / cm². 2 After assembly, the charge / discharge and cycle life of the full battery were tested.

[0217] The specific assembly and testing process is as follows: The battery is assembled using a self-made acrylic mold. The mold uses an acrylic sheet as a support and consists of carbon cloth (positive electrode current collector), negative electrode (MoO3 drop-coated electrode), sealing sheet, and stainless steel tabs. The specific assembly steps are as follows: Using insulated tweezers, assemble the battery in the following order: acrylic sheet, stainless steel tabs, negative electrode, sealing gasket, acrylic sheet, separator, sealing gasket, carbon cloth, stainless steel tabs, and acrylic sheet. After assembly, tighten the screws to ensure a seal, and add 1 mL of carbon cloth relative to the positive electrode area using a dropper. -2 The electrolyte. Constant current charge-discharge testing was performed using the Blue Battery testing system.

[0218] Figure 6 The MoO3 / / MnO2 full cell using the electrolytes of Example 1 and Comparative Example 1 was demonstrated at 0.5 mA / cm². -2 Cycle life diagrams at current density are shown. The results indicate that the full cell using Example 1 showed no significant capacity decay after 1500 cycles, while the full cell using Comparative Example 1 began to experience a sharp capacity decrease after approximately 600 cycles and completely failed after 800 cycles. These results verify that the proton-on-demand supply strategy is also effective in MoO3 / / MnO2 full cells with higher proton requirements, confirming its universality and superiority.

[0219] In summary, this invention utilizes the dynamic dissociation equilibrium of a weak acid to construct a proton-on-demand electrolyte, thereby achieving on-demand supply of protons during the MnO2 dissolution process, promoting complete electrochemical dissolution of MnO2, inhibiting the formation of "dead manganese," and thus significantly improving the cycle stability of the battery and the utilization efficiency of active materials.

[0220] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0221] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An electrolyte for aqueous manganese-based batteries, characterized in that, The electrolyte comprises: Electrolytes, including manganese salts; A weak acid is used to regulate the dynamic release of protons at the positive electrode / electrolyte interface, thereby enabling on-demand supply of protons at the positive electrode / electrolyte interface. and a solvent, wherein the solvent is deionized water; The pH range of the electrolyte is 2.0-3.5; During the charging and discharging process of the aqueous manganese-based battery, the electrolyte can achieve on-demand supply of protons at the positive electrode / electrolyte interface, promoting the efficient and reversible deposition and dissolution of manganese dioxide, the positive electrode active material.

2. The electrolyte for aqueous manganese-based batteries according to claim 1, characterized in that, The pKa of the weak acid is in the range of 3.0-6.0, preferably 3.5-5.5, and most preferably 3.8-5.

0.

3. The electrolyte for an aqueous manganese-based battery according to claim 1, characterized in that, In the electrolyte The anion in the weak acid and the manganese ion in the manganese salt are noncoordinated. The manganese salt is a noncoordinate anionic manganese salt.

4. The electrolyte for an aqueous manganese-based battery according to claim 1, characterized in that, In the electrolyte The stability constant of the complex between the anion in the weak acid and the manganese ion in the manganese salt is logK≤9. The stability constant of the complex between the anion and manganese ion in the manganese salt is logK≤9.

5. The electrolyte for aqueous manganese-based batteries according to claim 3 or 4, characterized in that, The weak acid includes one or more of acrylic acid, formic acid, propionic acid, glycolic acid, and ascorbic acid; The manganese salt includes one or more of manganese sulfate, manganese chloride, manganese perchlorate, manganese nitrate, and manganese bis(trifluoromethanesulfonate).

6. The electrolyte for an aqueous manganese-based battery according to claim 1, characterized in that, The electrolyte satisfies at least one of the following conditions: The concentration of the manganese salt in the electrolyte is 0.005-6.0 M; The electrolyte also includes a second soluble electrolyte salt, the type of which depends on the type of negative electrode that matches the positive electrode of the aqueous manganese-based battery. The concentration of the second soluble electrolyte salt is 0–3.0 M; The electrolyte also includes optional additives.

7. The method for preparing the electrolyte for an aqueous manganese-based battery as described in any one of claims 1-6, characterized in that, The method includes: dissolving manganese salt in deionized water to form a manganese salt aqueous solution, adding one or more weak acids to the manganese salt aqueous solution, adjusting the final pH value of the solution to 2.0-3.5 using the weak acids, and stirring evenly to obtain the electrolyte.

8. A water-based manganese-based battery, characterized in that, The battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the electrolyte is the aqueous manganese-based battery electrolyte according to any one of claims 1-6.

9. The aqueous manganese-based battery according to claim 8, characterized in that, The battery satisfies at least one of the following conditions: The positive electrode includes an unloaded current collector or a current collector loaded with MnO2 active material. The current collector is a three-dimensional high specific surface area metal or non-metal current collector. The loading method is pre-loading or in-situ electrodeposition loading. The pre-loading includes pre-electrodeposition loading or loading by co-coating or drop-coating with binder and conductive agent. The negative electrode includes a metallic negative electrode and a non-metallic negative electrode; the metallic negative electrode includes one or more of zinc, copper, lead, tin, bismuth, cadmium, manganese, and indium; the non-metallic negative electrode includes one or more of hydrogen, sulfur, carbon, molybdenum trioxide, sodium titanium phosphate, hexamolybdenum octasulfide, quinones, phenazines, and imides.

10. The electrolyte for aqueous manganese-based batteries as described in any one of claims 1-7 and the application of aqueous manganese-based batteries as described in any one of claims 8-9 in the field of secondary energy storage.

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