Electrolytic zinc-manganese aqueous system battery

Abstract

The application discloses an electrolytic zinc-manganese aqueous battery, which comprises a positive electrode, a zinc metal negative electrode and an electrolyte; the electrolyte comprises a manganese salt, a zinc salt, water, an acid and an electrolyte additive; and the electrolyte additive is hydroxymethyl (sub) dimethyl phosphate. The hydroxyl and phosphate groups in the hydroxymethyl (sub) dimethyl phosphate synergistically induce electrolysis effect. The phosphorus-oxygen double bond in the phosphate group can open the metal manganese and zinc cations in the complex electrolyte, and the metal manganese and zinc cations can quickly migrate to the electrode-electrolyte interface for electrochemical oxidation-reduction reaction under the guidance of the hydroxyl, so that the deposition-dissolution chemistry of the manganese dioxide and zinc cations is improved, and the catalytic electrolysis reaction kinetics is improved.

Description

Technical Field

[0001] This application relates to an electrolytic zinc-manganese aqueous battery, belonging to the field of aqueous battery electrolyte optimization technology. Background Technology

[0002] Batteries are a primary energy storage and conversion device. Their application in large-scale energy storage allows renewable energy sources such as solar, wind, and hydropower to be connected to the grid, ensuring electricity needs for industry, agriculture, households, and businesses. Compared to organic battery systems, aqueous batteries are widely studied due to their lower cost and higher safety.

[0003] Among various aqueous batteries, electrolytic MnO2-Zn batteries have attracted much attention due to their advantages such as high capacity, high output voltage, long cycle stability, and environmental friendliness, and are expected to be used in large-scale energy storage applications. The working principle of electrolytic MnO2-Zn batteries is based on Mn... 2+ / MnO2 cathode and Zn 2+ The solid / liquid phase deposition and dissolution reaction of the Zn anode involves two-electron transfer. The main electrode reactions of the battery are as follows:

[0004] positive electrode:

[0005] negative electrode:

[0006] overall: During charging, Mn 2+ The ions are oxidized and deposited on the positive electrode as solid MnO2, Zn 2+ The ions are reduced and form Zn metal on the negative electrode; during discharge, the MnO2 solid at the positive electrode and the Zn at the negative electrode gradually ionize into Mn. 2+ and Zn 2+ Ions, which then return to the electrolyte. Electrolytic MnO2-Zn batteries have inexpensive positive and negative electrodes and also possess a high theoretical specific capacity (positive electrode: 616 mAh g). -1 Negative electrode: 820mAh g -1 Furthermore, the MnO2 cathode has a high redox potential of 1.23V, while the Zn anode has a low redox potential of -0.76V. Combining the MnO2 cathode and the Zn anode can create a low-cost, high-output-voltage, and high-energy-density aqueous battery.

[0007] However, electrolytic MnO2-Zn batteries suffer from poor conductivity and slow reaction kinetics at the positive electrode, and uneven deposition, dendrite formation, and accompanying side reactions at the negative electrode. These problems severely hinder the development of electrolytic MnO2-Zn batteries. Furthermore, simply improving the deposition / dissolution chemistry of the MnO2 positive and Zn negative electrodes is insufficient to fully realize the electrochemical performance of electrolytic MnO2-Zn batteries. Therefore, this invention designs an electrolytic zinc-manganese aqueous battery optimized with dimethyl hydroxymethyl (DMOH), aiming to simultaneously enhance the electrolytic reaction kinetics of both the MnO2 positive and Zn negative electrodes through the synergistic effect of the hydroxyl and phosphate groups in DMOH, thereby improving the overall electrochemical performance of the electrolytic MnO2-Zn battery. Summary of the Invention

[0008] In view of this, the present invention provides an aqueous zinc-manganese secondary battery optimized with dimethyl hydroxymethyl (DMT) phosphate, aiming to at least partially solve the above-mentioned technical problems. The electrolytic zinc-manganese aqueous battery includes a positive electrode, a zinc metal negative electrode, and an electrolyte; the electrolyte includes manganese salt, zinc salt, water, acid, and a dimethyl hydroxymethyl (DMT) phosphate electrolyte additive. The present invention utilizes the synergistic effect of the hydroxyl and phosphate groups in dimethyl hydroxymethyl (DMT) phosphate to induce an electrolytic effect. Because the phosphorus-oxygen double bond in the phosphate group can open the complex with manganese and zinc cations in the electrolyte, they can rapidly migrate to the electrode-electrolyte interface under the guidance of the hydroxyl group to carry out electrochemical redox reactions, thereby improving the deposition and dissolution chemistry of manganese dioxide and zinc cations and catalyzing the electrolytic reaction kinetics.

[0009] This application provides an electrolytic zinc-manganese aqueous battery, which includes a positive electrode, a zinc metal negative electrode, and an electrolyte;

[0010] The electrolyte includes manganese salt, zinc salt, water, acid, and electrolyte additives;

[0011] The electrolyte additive is dimethyl hydroxymethyl phosphate.

[0012] Specifically, the dimethyl hydroxymethyl phosphonate mentioned in this invention refers to both dimethyl hydroxymethyl phosphate and dimethyl hydroxymethyl phosphonite, which are two names for the same substance. The CAS number is 24630-67-9, the English name is Dimethylhydroxymethylphosphonate, abbreviated as DHP, the molecular formula is C3H9O4P, and the structural formula is...

[0013] Optionally, the electrolyte additive may be one or more of dimethyl hydroxymethyl phosphate or additives containing both hydroxyl and phosphate groups.

[0014] Optionally, the manganese salt is selected from one or more of manganese acetate, manganese chloride, and manganese sulfate;

[0015] The zinc salt is selected from one or more of zinc iodide, zinc bromide, zinc chloride, and zinc sulfate.

[0016] Optionally, the positive electrode is selected from one or more of carbon felt, carbon cloth, carbon paper, conductive activated carbon film, graphene film, carbon nanotube film, graphene mesh, conductive graphite mesh, and conductive graphite plate.

[0017] Optionally, the negative electrode includes one or more of zinc sheets, zinc foil, and zinc plates.

[0018] Optionally, the manganese salt is a salt of divalent manganese ions; the zinc salt is a salt of divalent zinc ions;

[0019] In the electrolyte, the concentration of divalent manganese ions is 10. -2 ~10 mol / L; the concentration of divalent zinc ions is 10 -2 ~10 mol / L; the hydrogen ion concentration in the acid is 10 -5 ~10mol / L.

[0020] Optionally, in the electrolyte, the concentration of divalent manganese ions can be selected from any one of 0.02 mol / L, 0.2 mol / L, 2 mol / L, and 10 mol / L; the concentration of divalent zinc ions can be selected from any one of 0.02 mol / L, 0.2 mol / L, 2 mol / L, and 10 mol / L; and the concentration of hydrogen ions can be selected from 10 mol / L. -5 mol / L, 10 -4 mol / L, 10 -3 mol / L, 10 -2 The concentration of dimethyl hydroxymethyl phosphite can be selected from any one of 0.001 mol / L, 0.01 mol / L, 0.05 mol / L, and 0.1 mol / L.

[0021] Optionally, the anions of the manganese salt and the zinc salt are the same as the anions of the acid.

[0022] Optionally, the ion concentrations of the manganese salt anion, the zinc salt anion, and the acid anion are all 10. -3 ~10mol / L.

[0023] Optionally, the concentrations of the anions of manganese and zinc salts, as well as the anions of the acid radicals, can be selected from any one of 0.001 mol / L, 0.01 mol / L, 0.1 mol / L, 1 mol / L, 5 mol / L, and 10 mol / L.

[0024] Optionally, the acid is selected from one or more of phosphoric acid, acetic acid, hydrochloric acid, and sulfuric acid.

[0025] Optionally, the electrolytic zinc-manganese aqueous battery is an acidic or weakly acidic battery.

[0026] In this application, the electrolyte systems used in the assembled hydroxymethyl (dimethyl)phosphite-optimized manganese dioxide half-cell, zinc-copper asymmetric cell, zinc-zinc symmetric cell, and zinc-manganese full cell are all single-liquid systems.

[0027] Optionally, the concentration of the solute in the electrolyte is 0.1–1 g / mL;

[0028] The solutes include manganese salts, zinc salts, acids, and dimethyl hydroxymethyl phosphite.

[0029] Optionally, the solute concentration of the electrolyte can be selected from any one of 0.1 g / mL, 0.3 g / mL, 0.5 g / mL, 0.7 g / mL, and 1 g / mL.

[0030] Optionally, the concentration of dimethyl hydroxymethyl phosphite in the electrolyte is 10. -3 ~10 -1 mol / L.

[0031] Optionally, the concentration of dimethyl hydroxymethyl phosphite in the electrolyte can be selected from any one of 0.001 mol / L, 0.005 mol / L, 0.01 mol / L, 0.05 mol / L, and 0.1 mol / L.

[0032] The beneficial effects that this application can produce include:

[0033] The present invention relates to an electrolytic zinc-manganese aqueous battery optimized with dimethyl hydroxymethyl (DMH) phosphate. The electrolytic effect is induced by the synergistic effect of the hydroxyl and phosphate groups in DMH. Since the phosphorus-oxygen double bond in the phosphate group can open the complexation of manganese and zinc cations in the electrolyte, they can quickly migrate to the electrode-electrolyte interface under the guidance of the hydroxyl group to carry out electrochemical redox reactions. This is beneficial to improving the deposition and dissolution chemistry of manganese dioxide and zinc cations and catalyzing the electrolytic reaction kinetics.

[0034] Meanwhile, due to the strong electronegativity of the hydroxyl group in dimethyl hydroxymethyl phosphite, it helps the battery's positive / negative electrodes to have more active electronic states, easier charge transfer, and good conductivity, enabling the battery to maintain high coulombic efficiency and long cycle stability under large capacity. Attached Figure Description

[0035] Figure 1 This schematically illustrates the charging of MnO2 and DHP-MnO2 half-cells to 15 mAh cm⁻¹ under a constant voltage of 1.13 V. -2 The relationship between charging current response and time when the areal capacity is considered; Figure 1 b represents the charge-discharge curve of the half-cell. Figure 1 c represents the cyclic stability test.

[0036] Figure 2 This schematically illustrates a Zn-Cu asymmetric cell and a DHP-optimized Zn-Cu asymmetric cell at 1 mA cm⁻¹. -2 The charge / discharge curves below, Figure 2 b represents the long-cycle test of the asymmetric battery. Figure 2 c represents the charge-discharge curve of the asymmetric battery after 130–140 hours of operation. Figure 2 d represents a comparison of the long-cycle performance of Zn-Zn symmetric cells and DHP-optimized Zn-Zn symmetric cells.

[0037] Figure 3 ab schematically shows the XRD patterns of deposited MnO2 and DHP-MnO2 solids, as well as Zn and DHP-Zn metals. Figure 3 cd is the SEM morphology image of the deposited MnO2 and DHP-MnO2 solids. Figure 3 ef is a SEM image of the deposited Zn and DHP-Zn metal.

[0038] Figure 4 a schematically shows the XPS spectra of Mn3s in deposited MnO2 and DHP-MnO2 solids; Figure 4 b is the XPS plot of Zn 2p for Zn and DHP-Zn.

[0039] Figure 5 a schematic diagram shows the impedance spectra of MnO2 / / Zn cells and DHP-MnO2 / / Zn cells; Figure 5 b represents the ionic conductivity of the standard electrolyte and the DHP-optimized electrolyte. Figure 5 c represents the rate performance comparison of the full battery.

[0040] Figure 6 a schematic diagram shows the CV curves of MnO2 / / Zn cells and DHP-MnO2 / / Zn cells at 1 mV / s. Figure 6 b represents the charge-discharge curve of the full battery. Figure 6 c is a comparison chart of long-cycle operation of the full battery. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0042] In the process of developing this invention, it was discovered that the electrolytes in the electrolytes of electrolytic zinc-manganese aqueous batteries in related technologies are mainly manganese and zinc salts. Poor conductivity and slow reaction kinetics at the positive electrode, along with uneven deposition and dendrite formation at the negative electrode, lead to low capacity and poor cycle stability in electrolytic zinc-manganese batteries.

[0043] The electrolytic zinc-manganese aqueous battery designed in this invention utilizes the synergistic effect of hydroxyl (dimethyl) phosphate and phosphate groups in dimethyl phosphate to simultaneously enhance the electrolytic reaction kinetics of both the MnO2 cathode and the Zn anode, thereby improving the overall electrochemical performance of the electrolytic MnO2-Zn battery.

[0044] According to embodiments of the present invention, the manganese salt includes one or more of manganese acetate, manganese chloride, and manganese sulfate; the zinc salt includes one or more of zinc iodide, zinc bromide, zinc chloride, and zinc sulfate; and the optimization of the electrolyte includes one or more additives containing hydroxyl and phosphate groups.

[0045] According to embodiments of the present invention, the positive electrode comprises one or more of the following: carbon felt, carbon cloth, carbon paper, conductive activated carbon film, graphene film, carbon nanotube film, graphene mesh, conductive graphite mesh, and conductive graphite plate. The porous or 3D structure of the positive electrode is beneficial for increasing the contact area between the electrode and the electrolyte in the battery, thus promoting electrode reactions.

[0046] According to an embodiment of the present invention, the negative electrode includes one or more of zinc sheet, zinc foil, and zinc plate.

[0047] According to an embodiment of the present invention, the electrolytic zinc-manganese battery is an acidic zinc-manganese battery, and the acid in the electrolyte includes one or more of phosphoric acid, acetic acid, hydrochloric acid, and sulfuric acid.

[0048] In the embodiments of the present invention, all types of batteries assembled adopt a single-liquid battery system and do not require a separator, which can effectively reduce costs and avoid the battery performance being affected by the ionic conductivity limitation of the separator.

[0049] The invention will be further described in detail below with reference to electrochemical tests.

[0050] The batteries in Examples 1, 2, 5, and 6 of this invention were all evaluated and tested for electrochemical performance using a Shanghai Chenhua CHI760E electrochemical workstation and a Xinwei battery testing system. In Example 3, the crystal structure of the electrode material was characterized using X-ray powder diffraction (XRD, Rigaku, MiniFlex600, Japan), and the morphology and structure of the electrode material were characterized using field emission scanning electron microscopy (FESEM, JEOL, JSM6700-F, Japan). In Example 4, the elemental composition and content of the electrode material were characterized using X-ray photoelectron spectroscopy (XPS, Thermo Fisher, ESCALAB 250Xi, USA). Unless otherwise specified, DHP described in the embodiments of this invention refers to dimethyl hydroxymethyl (DMT).

[0051] Example 1

[0052] The MnO2 half-cell was assembled using carbon felt as the working electrode, an Ag / AgCl electrode as the reference electrode, and platinum foil as the counter electrode. The electrolyte was a mixed solution of 1M MnSO4 and 0.1M H2SO4. Electrodes with / without 0.05M DHP solution were used as controls. All electrodes were immersed in the electrolyte. The carbon felt required pretreatment to improve its hydrophilicity before use. The pretreatment process involved heat-treating 10 x 10 cm (length x width) carbon felt in a muffle furnace at 400°C for 2 hours. After heat treatment, the carbon felt was collected and cut as needed for battery assembly. The 3D structure of the carbon felt provides an effective electrolyte contact reaction channel for MnO2 deposition and stripping. The current response of the DHP-optimized / unoptimized MnO2 half-cells during charging was tested using a chronoamperometry method. Figure 1 As shown in Figure a, the response current is relatively high at the beginning of charging, then decreases sharply, and finally reaches a relatively stable state. This process is mainly due to the large instantaneous current on the carbon felt current collector at the start of charging. As charging continues, MnO2 gradually deposits on the positive electrode carbon felt, causing the response current to decrease sharply. Then, as MnO2 continues to deposit and completely covers the surface of the carbon fibers within the carbon felt, the response current eventually stabilizes. This was achieved during constant voltage charging to 15 mAh cm⁻¹. -2 During the process of achieving high areal capacity, the current response of the DHP-MnO2 half-cell was significantly improved by approximately 13.9 mA cm⁻¹ compared to the MnO2 half-cell. -2 The charging time has been reduced by approximately 27 minutes.

[0053] By charging the carbon felt electrode to 15 mAh cm⁻¹ at a constant voltage of 1.13 V. -2 The areal capacity was obtained, and then the voltage was obtained by discharging to 0V under a constant current of 15mA. Figure 1Figure b shows the charge-discharge curves of the MnO2 and DHP-MnO2 half-cells. The discharge curve of the MnO2 half-cell exhibits a gentle voltage plateau of approximately 0.95V, which is consistent with the MnO2 half-cell. 2+ The values ​​for the chemical reactions of MnO2 deposition and dissolution are close to the theoretical values. However, compared to the MnO2 half-cell, the DHP-MnO2 half-cell exhibits a higher discharge voltage plateau and a larger discharge capacity, indicating that DHP helps improve electrode reaction kinetics and MnO2 concentration. 2+ / Capacity of MnO2 electrolysis chemistry.

[0054] Figure 1 c represents the cycle stability test of DHP-optimized / unoptimized MnO2 / / Zn batteries. The coulombic efficiency of the MnO2 / / Zn battery gradually increases during the initial 30 cycles, then gradually decreases with increasing cycle count. After 360 cycles, the battery tends to fail. The coulombic efficiency of the DHP-optimized MnO2 / / Zn battery is significantly higher than that of the standard MnO2 / / Zn battery. The coulombic efficiency of the DHP-optimized MnO2 / / Zn battery shows a trend of first increasing and then decreasing with increasing cycle count, and it can maintain approximately 98% coulombic efficiency for stable cycling up to 700 cycles.

[0055] Example 2

[0056] Zn-Cu asymmetric and Zn-Zn symmetric cells were assembled and used to test the electrochemical performance of the zinc anode. Before use, the zinc foil was polished with 2000-grit sandpaper to remove its protective layer, exposing high-purity zinc metal for electrode reactions. The Zn-Cu asymmetric cell was assembled using copper foil as the positive electrode, glass fiber as the separator, zinc foil as the negative electrode, and a solution of 1M ZnSO4 and 0.1M H2SO4 (with or without 0.05M DHP) as the electrolyte. The Zn-Zn symmetric cell was assembled using two zinc foils as the positive and negative electrodes, separated by a glass fiber separator, with an electrolyte consisting of 1M ZnSO4 and 0.1M H2SO4 (with or without 0.05M DHP).

[0057] Figure 2 Figure a shows the charge-discharge curves of the first cycle of a Zn-Cu asymmetric cell and a DHP-optimized Zn-Cu asymmetric cell. Compared to the Zn-Cu asymmetric cell, the DHP-optimized Zn-Cu asymmetric cell exhibits a lower overpotential and a higher discharge capacity. Figure 2Long-cycle stability tests showed that the Zn-Cu asymmetric cell could only cycle for 150 cycles, while the DHP-optimized Zn-Cu asymmetric cell exhibited good cycle stability, achieving stable cycling for up to 2200 cycles. The DHP-optimized Zn-Cu asymmetric cell also showed a higher coulombic efficiency compared to the Zn-Cu asymmetric cell (DHP-optimized Zn-Cu: 99.95% vs Zn-Cu: 96.55%). Figure 2 The Zn-Cu asymmetric cell in c experienced a short circuit after 133.5 hours of operation. In contrast, the voltage curve of the DHP-optimized Zn-Cu asymmetric cell remained almost unchanged after 140 hours of operation, revealing the good reversibility of the DHP-optimized Zn-Cu asymmetric cell.

[0058] Figure 2 The results show that the polarization of the Zn / / Zn symmetric cell gradually increases after more than 150 cycles, and the cell fails due to a short circuit around 250 cycles. In contrast, the DHP-optimized Zn / / Zn symmetric cell exhibits superior cycling performance at 1 mAh cm⁻¹. -2 It exhibits an exceptionally long lifespan of up to 2000 hours at its capacity and maintains excellent reversible zinc plating / stripping behavior.

[0059] Example 3

[0060] The MnO2 and DHP-MnO2 solid cathodes deposited in Example 1 and the Zn and DHP-Zn metal anodes deposited in Example 2 were characterized by XRD to further analyze the phase and structural characteristics of the MnO2 cathode and Zn anode materials.

[0061] Figure 3 The strong, broad peaks marked with an asterisk in α belong to carbon felt. The three strong diffraction peaks at (311), (400), and (511) belong to the α-phase MnO2, corresponding to standard JCPDS card number 42-1169. No diffraction peaks originating from any other impurities or intermediate phases were detected, indicating the high purity of the deposited sample. Figure 3 The asterisked peaks in figure b originate from the copper substrate. The five diffraction peaks in the figure belong to zinc metal, corresponding to standard JCPDS card number 99-0110. The sharp XRD peaks of zinc metal in the figure reveal that the deposited zinc has good crystallinity.

[0062] Figure 3Image c shows the morphology of the MnO2 cathode deposited on the carbon felt in an additive-free electrolyte system. Large-sized agglomerates of MnO2 solids were observed on the carbon felt, and these solids were clearly cracked. The presence of these cracks in the deposited MnO2 solids leads to poor contact between the MnO2 solids and the carbon felt, hindering subsequent MnO2 deposition. Furthermore, the presence of these cracks also makes it easier for MnO2 to detach, thus affecting battery life. However, in the DHP-modified electrolyte system, the morphology of the MnO2 solids deposited on the carbon felt is more uniform, and the MnO2 solids are tightly wrapped around the carbon felt electrode. Figure 3 As shown in e, the deposited MnO2 solids in the electrolyte system regulated by DHP additives effectively reduced cracks, revealing that the regulating effect of DHP additives is beneficial to the deposition of MnO2.

[0063] Figure 3 Figure d shows the morphology of zinc metal deposited on a copper substrate in an additive-free electrolyte system. It can be seen from the figure that the deposited zinc particles have a relatively rough surface and are unevenly distributed. Uneven zinc particle deposition affects the electric field distribution, thus impacting the battery's electrochemical performance. However, in the electrolyte system regulated by DHP additives, the deposited zinc particles have a more uniform morphology and distribution, which is beneficial for homogenizing the electric field and thus promoting improved battery electrochemical performance.

[0064] Example 4

[0065] The MnO2 and DHP-MnO2 solid cathodes deposited in Example 1 and the Zn and DHP-Zn metal anodes deposited in Example 2 were characterized by XPS to further analyze the elemental composition and valence state of the electrode materials.

[0066] Figure 4 a represents the XPS binding energy spectra of Mn 2p in MnO2 and DHP-MnO2. Two distinct energy peaks near 83.5 and 90.2 eV belong to the Mn 3s peak. The average oxidation state (AOS) of Mn can be calculated using the formula: AOS = 8.95 - 1.13ΔEs (eV), where ΔEs is the energy difference between the main peak and its companion peak in the Mn 3s peak. In the MnO2 half-cell, based on the 5.05 eV splitting energy of the Mn 3s peak of the deposited MnO2 during the charging process, the average oxidation state of MnO2 is calculated to be 3.24 valence using the above formula. This indicates that in the MnO2 half-cell, Mn... 2+In the deposition chemistry of MnO2, the actual number of electrons transferred by Mn ions is 1.24 (3.24-2). Similarly, based on the splitting energy of 4.78 eV between the two splitting peaks of the Mn 3s level, the average oxidation state of Mn in DHP-MnO2 is calculated to be 3.55, indicating that the actual number of electrons transferred by Mn ions in the DHP-MnO2 electrode is 1.55. The average oxidation state of Mn in DHP-MnO2 is higher than that of Mn in MnO2, indicating that the DHP additive facilitates the oxidation of MnO2, thus promoting the deposition of MnO2 cathode.

[0067] Figure 4 b shows that the Zn metal deposited in the Zn half-cell exhibits Zn 2p at 1045.8 and 1023.9 ​​eV, respectively. 1 / 2 and Zn 2p 3 / 2 The two binding energy peaks. In the DHP-Zn half-cell deposited Zn anode, the Zn 2p peaks are... 1 / 2 and Zn 2p 3 / 2 The peak in the region shifts by 0.6 eV towards lower binding energies, which means that the Zn in the electrolyte... 2+ Restore to Zn 0 The reduction is more thorough. XPS analysis of both the MnO2 cathode and Zn anode revealed that the DHP additive promotes the oxidation of the MnO2 cathode and the reduction of the Zn anode, thus resulting in a more complete electrode reaction in the battery.

[0068] Example 5

[0069] The MnO2 half-cell assembled in Example 1 and the Zn half-cell assembled in Example 2 were matched to assemble a full cell. The MnO2 / / Zn full cell was assembled using carbon felt as the positive electrode current collector, zinc foil as the negative electrode, and 1M MnSO4 + 1M ZnSO4 + 0.1M H2SO4 as the standard electrolyte. As a comparison, a DHP-optimized MnO2 / / Zn cell was assembled by adding 0.05M DHP solution to the standard electrolyte, serving as a control cell. The electrochemical performance of the assembled MnO2 / / Zn cell and the DHP-optimized MnO2 / / Zn cell was characterized to further evaluate the comprehensive role of DHP in the MnO2 / / Zn full cell.

[0070] Figure 5a represents the electrochemical impedance spectroscopy (EIS) spectra of DHP-optimized / unoptimized MnO2 / / Zn cells. The results show that compared to the MnO2 / / Zn cell (Ri = 4.34 Ω, Rct = 4.58 Ω), the DHP-optimized MnO2 / / Zn cell exhibits lower internal resistance (Ri = 1.63 Ω) and charge transfer resistance (Rct = 1.52 Ω), revealing the superior electrochemical activity of the DHP-optimized MnO2 / / Zn cell in terms of charge transfer rate and ion diffusion kinetics.

[0071] Figure 5 b shows that the conductivity of the DHP-optimized electrolyte is significantly higher than that of the unoptimized electrolyte, indicating that DHP is beneficial for improving the conductivity of the electrolyte. This also suggests that the high conductivity of the electrolyte due to the presence of DHP is more conducive to promoting the chemical reaction at the electrode-electrolyte interface, thereby improving the electrochemical performance of the battery.

[0072] Figure 5 c describes the rate performance of DHP-optimized / unoptimized MnO2 / / Zn batteries at various discharge rates from 1C to 10C. The discharge capacity, voltage plateau, and coulombic efficiency of the DHP-optimized MnO2 / / Zn battery gradually decrease with increasing discharge rate from 1C to 10C. After switching back to 1C from 10C, the DHP-optimized MnO2 / / Zn battery recovers to its initial voltage plateau and approximately 14.32 mAh cm⁻¹. -2 The initial discharge capacity and coulombic efficiency were achieved. The DHP-optimized MnO2 / / Zn battery exhibited superior rate performance compared to the unoptimized MnO2 / / Zn battery. Compared to the MnO2 / / Zn battery, the DHP-optimized MnO2-Zn battery demonstrated higher discharge capacity and coulombic efficiency at high current densities, indicating that DHP in the electrolyte not only promotes the reaction kinetics of the MnO2-Zn battery but also contributes to improving the battery's capacity.

[0073] Example 6

[0074] The electrochemical performance of the MnO2 / / Zn battery assembled in Example 5 and the DHP-optimized MnO2 / / Zn battery were tested to further analyze the functional role of the DHP regulator in the MnO2 / / Zn battery.

[0075] Figure 6 a represents the DHP-optimized / unoptimized MnO2 / / Zn cell at a scan rate of 1 mV s -1 The CV curves are shown. Compared to the MnO2 / / Zn battery, the larger CV curve area of ​​the DHP-optimized MnO2-Zn battery suggests that it has a higher capacity, and also reveals that DHP helps to promote the capacity improvement of MnO2 / / Zn batteries.

[0076] Figure 6 b. DHP-optimized MnO2-Zn battery at 15mAh cm⁻¹ -2 The surface capacity is 1C (15mAcm). -2 During rate discharge, it exhibited a gentle discharge plateau of approximately 1.92V and a capacity of 11.95mAh cm⁻¹. -2 The discharge capacity is significantly higher than that of the discharge plateau and discharge capacity (1.85V and 10.52mAh cm⁻¹) of the MnO₂-Zn battery at a 1C rate. -2 ).

[0077] Figure 6 The cycle life test results of c show that the MnO2 / / Zn battery has a cycle life of 15mAh cm⁻¹. -2 Despite its high area capacity, it could only maintain a low coulombic efficiency of about 80% for 450 cycles and failed after 580 cycles. In contrast, the DHP-optimized MnO2 / / Zn battery, even at 15mAh cm⁻¹, -2 Even after 1000 stable cycles at a high areal capacity, the DHP-optimized MnO2 / / Zn battery still maintains a good coulombic efficiency of approximately 92%. The high energy efficiency and long-term cycle stability maintained at high areal capacity highlight the advantages of DHP functionality. This high-performance DHP-optimized MnO2 / / Zn battery has enormous development potential for practical applications in large-scale energy storage.

[0078] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An electrolytic zinc-manganese aqueous battery, characterized in that, The electrolytic zinc-manganese aqueous battery includes a positive electrode, a zinc metal negative electrode, and an electrolyte. The electrolyte includes manganese salt, zinc salt, water, acid, and electrolyte additives; The electrolyte additive is dimethyl hydroxymethyl phosphate.

2. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The manganese salt is selected from one or more of manganese acetate, manganese chloride, and manganese sulfate.

3. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The zinc salt is selected from one or more of zinc iodide, zinc bromide, zinc chloride, and zinc sulfate.

4. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The positive electrode is selected from one or more of the following: carbon felt, carbon cloth, carbon paper, conductive activated carbon film, graphene film, carbon nanotube film, graphene mesh, conductive graphite mesh, and conductive graphite plate.

5. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The manganese salt is a salt of divalent manganese ions; the zinc salt is a salt of divalent zinc ions; In the electrolyte, the concentration of divalent manganese ions is 10. -2 ~10 mol / L; the concentration of divalent zinc ions is 10 -2 ~10 mol / L; the hydrogen ion concentration in the acid is 10 -5 ~10mol / L.

6. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The anions of the manganese salt and the zinc salt are the same as the anions of the acid.

7. The electrolytic zinc-manganese aqueous battery according to claim 6, characterized in that, The concentrations of the anions of the manganese salt, the zinc salt, and the anions of the acid are all 10. -3 ~10mol / L.

8. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The acid is selected from one or more of phosphoric acid, acetic acid, hydrochloric acid, and sulfuric acid.

9. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, The concentration of the solute in the electrolyte is 0.1–1 g / mL; The solutes include manganese salts, zinc salts, acids, and dimethyl hydroxymethyl phosphite.

10. The electrolytic zinc-manganese aqueous battery according to claim 1, characterized in that, In the electrolyte, the concentration of dimethyl hydroxymethyl phosphite is 10. -3 ~10 -1 mol / L.

Images