Electrolytic mn02-zn water system battery

Abstract

The disclosure provides a cation accelerator optimized electrolytic type MnO2-Zn aqueous battery, comprising: a positive electrode, the positive electrode being MnO2; a negative electrode, the negative electrode being Zn; an electrolyte system, the electrolyte system being an acidic solution containing metal cations, wherein the metal cations at least simultaneously include Mn 2+ , Zn 2+ ; a cation accelerator, which forms a hydrated ion structure by combining with metal cations Mn 2+ or Zn 2+ , water molecules, adjusts the solvation structure of metal cations Mn 2+ , Zn 2+ , promotes the deposition and dissolution process of metal cations Mn 2+ , Zn 2+ , and improves the electrochemical performance of the electrolytic type MnO2-Zn aqueous battery.

Description

Technical Field

[0001] This disclosure relates to the field of aqueous zinc-manganese battery energy storage technology, and in particular to an electrolytic MnO2-Zn aqueous battery. Background Technology

[0002] The excessive consumption of fossil fuels and the excessive emission of carbon dioxide (CO2) greenhouse gases have caused a severe energy crisis and environmental pollution problems. The rational development and utilization of new clean and renewable energy sources are crucial for the sustainable development of humankind. However, clean energy sources such as wind and solar power are sporadic and indirect, making direct grid integration difficult. Therefore, large-scale energy storage technologies are needed to achieve time-shifting of electricity to meet the sporadic electricity demands of users. While lithium-ion batteries, as a representative example, have high energy and power densities and have been commercially used for decades, the use of flammable organic electrolytes limits their development in large-scale energy storage applications. Therefore, the development of highly safe and low-cost aqueous batteries is of great significance.

[0003] Among various aqueous batteries, electrolytic MnO2-Zn batteries have attracted much attention due to their advantages such as low cost, high output voltage, high safety, and environmental friendliness, and are expected to be applied in large-scale energy storage. Unlike traditional aqueous zinc-manganese batteries based on the single-electron transfer reaction of the MnO2 cathode, electrolytic MnO2-Zn batteries are mainly based on the cathode (MnO2 / Mn... 2+ ) and negative electrode (Zn / Zn 2+ Solid / liquid phase reactions involving two electron transfers. The advantages of electrolytic MnO2-Zn batteries mainly lie in: reversible MnO2 / Mn... 2+ The positive electrode deposition / dissolution reaction exhibits an appropriate redox potential of 1.23 V vs SHE and a capacity of 616 mAh g. -1 High theoretical specific capacity, and reversible Zn / Zn 2+ The negative electrode deposition / dissolution reaction exhibits a low redox potential of -0.76V vs SHE and a capacity of 820mAh g. -1 High theoretical specific capacity. Combining inexpensive MnO2 cathode and Zn anode holds promise for assembling an ideal aqueous battery with low cost and high energy density.

[0004] However, the development of MnO2-Zn batteries is still hindered by several problems, such as low energy density, poor electrode reaction reversibility, slow solid-state charge storage reaction, large overpotential caused by electrochemical polarization, ion intercalation, and voltage curve tilt caused by phase transition processes. This is especially true for the cathode (MnO2 / Mn...). 2+The slow reaction kinetics result in low energy efficiency (<50%) for MnO2-Zn batteries at high rates. Especially at larger deposition capacities, the slow deposition / dissolution reaction often leads to the gradual accumulation of inactive materials on both the positive and negative electrodes, forming "dead MnO2" and "dead Zn", which significantly impairs the cycle life of MnO2-Zn batteries.

[0005] To enhance the reaction kinetics of MnO2-Zn batteries, various methods applied to the positive electrode have been explored, including preparing porous materials, constructing ionic and electronic conductive frameworks, embedding conductive polyaniline and phosphate ions, introducing pseudocapacitance, and controlling oxygen vacancies or nitrogen doping. Various strategies to address Zn anode problems have also been investigated, such as developing novel three-dimensional electrodes, surface coating technologies, salt-in-water electrolytes, and electrolyte additives. However, simply improving the MnO2 / Mn ratio... 2+ Positive electrode deposition / dissolution chemistry or unilateral improvement of Zn / Zn 2+ The electroplating / stripping reaction at the negative electrode cannot fully realize the electrochemical performance of the MnO2-Zn battery. Therefore, this disclosure presents a cation accelerator scheme to simultaneously promote the reaction kinetics of both the positive and negative electrodes and significantly improve the overall performance of the electrolytic MnO2-Zn battery. Summary of the Invention

[0006] To at least partially address at least one of the aforementioned technical deficiencies, embodiments of this disclosure provide a cation accelerator-optimized electrolytic MnO2-Zn aqueous battery, which utilizes a cation accelerator to react with metal cations Mn... 2+ or Zn 2+ And the hydrated ion structure coordinated by the cation accelerator for water molecule formation, regulating the metal cation Mn 2+ Zn 2+ The solvation structure promotes the metal cation Mn 2+ Zn 2+ The deposition and dissolution process improves the electrochemical performance of electrolytic MnO2-Zn aqueous batteries.

[0007] To achieve the above objectives, as an embodiment of one aspect of this disclosure, an electrolytic MnO2-Zn aqueous battery optimized for cation accelerators is provided, comprising: a positive electrode made of MnO2; a negative electrode made of Zn; and an electrolyte system, wherein the electrolyte system is an acidic solution containing metal cations, wherein the metal cations at least simultaneously include Mn. 2+ Zn 2+ ; Cation accelerator, through the above-mentioned metal cation Mn 2+ or Zn 2+ Water molecules form a hydrated ionic structure, regulating the above-mentioned metal cation Mn2+ Zn 2+ The solvation structure of the above-mentioned metal cation Mn promotes 2+ Zn 2+ The deposition and dissolution process.

[0008] According to embodiments of this disclosure, the above-described cation accelerator and the above-described metal cation Mn 2+ A manganese complex is formed, and the manganese complex coordinates with H2O molecules to form a hydrated manganese ion structure coordinated with the cation accelerator; the cation accelerator and the metal cation Zn 2+ A zinc complex is formed, and the zinc complex coordinates with H2O molecules to form a zinc hydrated ion structure coordinated with a cation accelerator.

[0009] According to embodiments of this disclosure, the cation accelerator includes any one of polyvinyl alcohol, dimethyl sulfoxide, and polyvinylpyrrolidone, preferably polyvinylpyrrolidone.

[0010] According to embodiments of this disclosure, the concentration range of the cation accelerator in the electrolyte system is 0.001 mmol / L to 0.1 mmol / L.

[0011] According to embodiments of this disclosure, the electrolyte system described above is a single-liquid battery system.

[0012] According to embodiments of this disclosure, the pH value of the electrolyte system described above is 0.1 to 2.

[0013] According to embodiments of this disclosure, the energy level of the highest occupied molecular orbital in the above-described manganese hydrated ion structure is higher than that of [Mn(H2O)6). 2+ The energy level of the highest occupied molecular orbital; the energy level of the highest occupied molecular orbital in the above zinc hydrate ion structure is higher than that of [Zn(H2O)6). 2+ The energy level of the highest occupied molecular orbital.

[0014] According to embodiments of this disclosure, the lowest unoccupied molecular orbital energy level of the manganese hydrated ion structure coordinated in the above-described cation accelerator is lower than [Mn(H2O)6). 2+ The lowest occupied molecular orbital energy level; the lowest unoccupied molecular orbital energy level of the zinc hydrate ion structure coordinated by the above cation accelerator is lower than [Zn(H2O)6). 2+ The lowest occupied molecular orbital energy level.

[0015] According to embodiments of this disclosure, the desolvation energy of the manganese hydrated ion structure coordinated in the above-described cation accelerator is lower than that of [Mn(H2O)6). 2+ The desolvation energy of the zinc hydrate ion structure coordinated by the above cation accelerator is lower than that of [Zn(H2O)6).2+ Desolvation energy.

[0016] According to embodiments of this disclosure, Mn in the above-described electrolyte system 2+ The concentration range of Zn ions is 0.001 mol / L to 10 mol / L. 2+ The concentration range of ions is from 0.001 mol / L to 10 mol / L.

[0017] The cation accelerator-optimized electrolytic MnO2-Zn aqueous battery provided in the above embodiments of this disclosure, by adding a cation accelerator to the electrolyte system to adjust the solvation structure of metal cations, accelerates the migration of metal cations in the electrolyte system, promotes sufficient charge transfer between the electrode and electrolyte interface, and simultaneously improves the MnO2 / Mn ratio of the positive electrode. 2+ and negative electrode Zn / Zn 2+ The transformation kinetics promote Mn 2+ / Zn 2+ The deposition and dissolution process of metal cations improves the electrochemical performance of electrolytic MnO2-Zn aqueous batteries. Attached Figure Description

[0018] Figure 1 Part a in the text refers to the metal cation Mn in the electrolyte of an exemplary embodiment of this disclosure. 2+ Zn 2+ In electrolytic MnO2-Zn batteries, [Mn(H2O)6] is formed through coordination with water. 2+ [Zn(H2O)6] 2+ A schematic diagram of the structure and a schematic diagram of the hydrated ion structure coordinated with the accelerator and water in the electrolytic MnO2-Zn battery optimized by the cation accelerator to form a cation accelerator coordinated hydrated ion structure.

[0019] Figure 1 Part b in the text refers to the metal cation Mn in an electrolytic MnO2-Zn aqueous battery. 2+ Zn 2+ A schematic diagram of the charge transfer reaction mechanism at the electrode-electrolyte interface;

[0020] Figure 1 Part c is a schematic diagram of the charge transfer reaction mechanism at the electrode-electrolyte interface in a cation accelerator optimized electrolytic MnO2-Zn aqueous battery according to an exemplary embodiment of this disclosure.

[0021] Figure 2 Metal cation Mn, which is an exemplary embodiment of this disclosure 2+ Zn 2+Numerical comparison of the desolvation energies of coordination structures in electrolytic MnO2-Zn aqueous batteries and coordination structures in cation accelerator-optimized MnO2-Zn aqueous batteries;

[0022] Figure 3 Part a in the text is the analysis of the surface electrostatic potential of van der Waals molecules in H2O and cation accelerators.

[0023] Figure 3 The b part is water-coordinated Mn 2+ or Zn 2+ Van der Waals molecular surface electrostatic potential analysis and cation accelerator, metal cation Mn 2+ or Zn 2+ Comparison of van der Waals surface electrostatic potential analysis of hydrated ions coordinated by cation accelerators for water molecule formation;

[0024] Figure 4 Mn coordinated with water 2+ or Zn 2+ HOMO level, LUMO level and cation accelerator, metal cation Mn 2+ or Zn 2+ A comparison diagram of the HOMO and LUMO energy levels of the hydrated ion structure coordinated by the cation accelerator for water molecule formation.

[0025] Figure 5 A comparison graph of ESW tests of an electrolytic MnO2-Zn aqueous battery and a cation accelerator-optimized electrolytic MnO2-Zn aqueous battery, which is an exemplary embodiment of this disclosure.

[0026] Figure 6 The CV curves of the MnO2 positive electrode half-cell in an electrolytic MnO2-Zn aqueous battery are shown at scan rates from 0.1 mV / s to 1 mV / s. Part a is the CV curve without the addition of a cation accelerator, part b is the CV curve with the addition of a cation accelerator, and part c is a comparison of the cycle performance with and without the addition of a cation accelerator.

[0027] Figure 7 The CV curves of the Zn anode half-cell in an electrolytic MnO2-Zn aqueous battery are shown at scan rates from 0.1 mV / s to 1 mV / s. Part a is the CV curve without the addition of a cation accelerator, part b is the CV curve with the addition of a cation accelerator, and part c is a comparison of the cycle performance with and without the addition of a cation accelerator.

[0028] Figure 8Discharge curves of an electrolytic MnO2-Zn full cell and a cation accelerator-optimized electrolytic MnO2-Zn full cell at different rates, representing an exemplary embodiment of this disclosure.

[0029] Figure 9 A comparison graph showing the rate performance of an electrolytic MnO2-Zn full cell and a cation accelerator-optimized electrolytic MnO2-Zn full cell, representing an exemplary embodiment of this disclosure.

[0030] Figure 10 A comparison chart of the cycle stability test results of an electrolytic MnO2-Zn aqueous battery and a cation accelerator-optimized electrolytic MnO2-Zn aqueous battery, which are exemplary embodiments of this disclosure, at a high rate of 20C. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0032] The dual deposition / dissolution reaction of electrolytic MnO2-Zn batteries is based on the deposition / dissolution reaction of metal cations: during charging, the positive electrode is formed by the deposition / dissolution of MnO2-Zn cations. 2+ The deposition is MnO2 (Mn 2+ →Mn 4+ The negative electrode is composed of Zn. 2+ Reduced to Zn(Zn 2+ →Zn 0 During discharge, MnO2 in solid state is ionized at the positive electrode. 2+ The negative electrode is ionized from Zn. 2+ These ionized cations then return to the electrolyte. Therefore, improving the deposition / dissolution reaction of cations is beneficial to enhancing the electrochemical performance of electrolytic MnO2-Zn batteries at high rates (high current densities).

[0033] However, researchers have focused primarily on the reactions between metal ions in MnO2-Zn batteries, often neglecting the coordination effects between metal ions and water. In electrolytic MnO2-Zn batteries, typically each transition metal ion (MnO2-Zn) in the electrolyte system... 2+ / Zn 2+ It can combine with up to 6 H2O molecules to form a stable coordinated hydrated ion structure: [Mn(H2O)6] 2+ and [Zn(H2O)6] 2+ They undergo redox reactions at the interface between the positive and negative electrodes during charging and discharging, respectively. The reaction principle can be described as follows:

[0034] positive electrode: negative electrode: overall: The solvation / desolvation process of transition metal ions at the electrode-electrolyte interface is likely a major factor determining the speed of the electrochemical conversion reaction and may be the reason for the slow kinetics of electrolytic MnO2-Zn batteries. The difficulty in desolvation of metal cations in MnO2-Zn batteries leads to low energy efficiency and poor cycle life at large deposition capacities, severely limiting the future practical application of electrolytic MnO2-Zn batteries.

[0035] According to the general inventive concept of this disclosure, an electrolytic MnO2-Zn aqueous battery with cation accelerator optimization is provided, comprising: a positive electrode made of MnO2; a negative electrode made of Zn; and an electrolyte system, wherein the electrolyte system is an acidic solution containing metal cations, wherein the metal cations at least simultaneously include Mn. 2+ Zn 2+ ; Cation accelerator, through interaction with metal cations Mn 2+ or Zn 2+ Water molecules form a hydrated ionic structure, regulating the metal cation Mn 2+ Zn 2+ The solvation structure promotes the metal cation Mn 2+ Zn 2+ The deposition and dissolution process.

[0036] The electrolytic MnO2-Zn aqueous battery provided in this disclosure improves the solvation structure of metal cations by adding a cation accelerator to the electrolyte system, thereby accelerating the migration of metal cations in the electrolyte system and promoting sufficient charge transfer at the electrode-electrolyte interface. 2+ and negative electrode Zn / Zn 2+ The transformation kinetics promote the transformation of Mn 2+ / Zn 2+ The deposition and dissolution process of metal cations improves the electrochemical performance of electrolytic MnO2-Zn aqueous batteries.

[0037] Figure 1 The right side of part a in the diagram schematically illustrates an electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator, comprising a cation accelerator and metal cations MnO2 and ZnO2. 2+ or Zn 2+ The manganese hydrated ion structure CA-[Mn(H2O)5] is coordinated with the cation accelerator of water molecules. 2+ The zinc hydrate ion structure CA-[Zn(H2O)5] coordinated with the cation accelerator 2+The diagram shows the structure, where "CA" represents the cation accelerator "polyvinylpyrrolidone (PVP)". (Refer to...) Figure 1 As shown in section c of this disclosure, the charge transfer reaction mechanism of coordinated ions at the electrode-electrolyte interface in the electrolytic MnO2-Zn aqueous battery reveals that CA-[Mn(H2O)5]... 2+ Structure and CA-[Zn(H2O)5] 2+ The structure not only carries cations to the electrode surface, but also accelerates the desolvation process, thus speeding up the deposition and dissolution reactions of the MnO2 cathode and Zn anode.

[0038] In contrast Figure 1 The left side of part a schematically illustrates the metal cation MnO2 in an electrolytic MnO2-Zn aqueous battery without a cation accelerator. 2+ Formation of [Mn(H2O)6] 2+ Zn 2+ Formation of [Zn(H2O)6] 2+ A structural diagram. Figure 1 Part b shows the electrolytic MnO2-Zn aqueous battery without a cation accelerator, where the metal cation Mn... 2+ and Zn 2+ It coordinates with a maximum of six water molecules in the electrolyte system, forming a stable water-coordinated [Mn(H2O)6] molecule. 2+ and [Zn(H2O)6] 2+ Structure: Water-coordinated [Mn(H2O)6] 2+ and [Zn(H2O)6] 2+ The structure gradually diffuses to the electrode surface, making it difficult to remove the coordinated water, resulting in a positive electrode MnO2 / Mn 2+ Chemical and negative electrode Zn / Zn 2+ Chemical transformation reactions are slow.

[0039] In some embodiments of this disclosure, the selection of cation accelerators should have some universal characteristics: (1) materials with multiple coordination with metal cations; (2) high electronic and ionic conductivity to achieve rapid solvation / desolvation of metal cations; (3) low viscosity to ensure good conductivity of the electrolyte system; (4) good dispersibility to avoid uneven distribution of metal cations; (5) high surface activity to facilitate the reaction between the electrode and electrolyte interface; (6) low cost to reduce battery cost; (7) non-toxic or low toxicity to ensure environmental friendliness; (8) non-flammability to ensure safety; (9) water solubility to enable its application in aqueous batteries; and (10) high chemical and electrochemical stability to improve battery cycle performance, etc.

[0040] In some embodiments of this disclosure, the cation accelerator includes any one of polyvinyl alcohol (PVA), dimethyl sulfoxide (DMSO), and polyvinylpyrrolidone (PVP). For example, polyvinylpyrrolidone (PVP) can be selected because the PVP molecule can simultaneously accelerate the electrolysis reaction kinetics of both the MnO2 cathode and the Zn anode using only the oxygen functional group on the lactam ring, possessing all the aforementioned characteristics, and is one of the promising cation accelerators.

[0041] In some embodiments of this disclosure, the concentration range of the cation accelerator in the electrolyte system includes 0.001 mmol / L to 0.1 mmol / L, wherein the optimized concentration of the cation accelerator in the electrolyte system is 0.07 mol / L. The content of the cation accelerator affects the diffusion and migration of metal cations in the electrolyte system. If the content of the cation accelerator in the electrolyte system is too low, the cation accelerator molecules cannot fully exert their performance; if the content of the cation accelerator is too high, the cation accelerator will increase the solution viscosity and restrict ion migration.

[0042] In some embodiments of this disclosure, the cation accelerator-optimized MnO2-Zn aqueous battery includes: a positive electrode, and a 1cm thick electrode with a thickness of 3mm. -2 Carbon felt; negative electrode, 3mm thick, 1cm -2 The electrolyte system consisted of a zinc sheet and a mixture of 1 mol / L MnSO4, 1 mol / L ZnSO4, 0.1 mol / L H2SO4, and 0.07 mmol / L PVP. Polyvinylpyrrolidone (PVP) was used as the cation exchange accelerator. The optimized MnO2-Zn aqueous battery with the above cation exchange accelerator was used as the model for theoretical calculations, yielding the following results:

[0043] (1) During battery cycling, Mn 2+ and Zn 2+ The coordinated hydrated ion structure needs to undergo a desolvation process to remove the cation accelerator; then it migrates to the electrode-electrolyte interface to undergo a redox reaction. (Refer to...) Figure 2 The results shown indicate that [Mn(H2O)6] is coordinated by water. 2+ and [Zn(H2O)6] 2+ The structures provided by these structures have desolvation energies of -10.05 eV / atom and -14.91 eV / atom, respectively, revealing the water-coordinated [Mn(H2O)6] structure in the electrolyte system. 2+ and [Zn(H2O)6] 2+ Mn in the structure 2+ and Zn 2+Cations are difficult to remove their coordinated water. In contrast, the hydrated ion structure CA-[Mn(H2O)5] coordinated by cation accelerators is much more efficient. 2+ and CA-[Zn(H2O)5] 2+ The desolvation energies provided were -1.24 eV / atom and -3.52 eV / atom, respectively, indicating that the cation accelerator facilitates the desolvation of the metal cation Mn. 2+ and Zn 2+ The ionization of MnO2 / Mn can thus accelerate the ionization of MnO2 / Mn 2+ and Zn / Zn 2+ Electrolytic kinetics of the reaction. Here, "desolvation energy" refers to the energy required for the desolvation process.

[0044] (2)Reference Figure 3 As shown in section a, the van der Waals surface electrostatic potential (ESP) analysis of H2O and the cation accelerator reveals that the oxygen on the lactone ring of the polyvinylpyrrolidone (PVP) cation accelerator has a more negative ESP value than the oxygen in water molecules, indicating that the positively charged metal cation Mn 2+ or Zn 2+ It has a stronger interaction with oxygen on the cation accelerator "polyvinylpyrrolidone (PVP)," thereby enabling the cation accelerator molecules in the electrolyte system to preferentially capture the ionized metal cations Mn in the electrolyte system. 2+ and Zn 2+ Forming CA-Mn 2+ Manganese complexes and CA-Zn 2+ The zinc complex then coordinates with H2O molecules to form cation-accelerator coordinated manganese hydrated ion structures CA-[Mn(H2O)5]. 2+ The zinc hydrate ion structure CA-[Zn(H2O)5] 2+ .

[0045] (3)Reference Figure 3 As shown in the comparison diagram of the van der Waals molecular surface electrostatic potential analysis in section b, the water-coordinated [Mn(H2O)6]... 2+ and [Zn(H2O)6] 2+ The minimum electrostatic potential of the structure originates from the lone pair of electrons of O in the coordinated water molecule, and the manganese hydrated ion structure CA-[Mn(H2O)5] coordinated by the cation accelerator. 2+ The zinc hydrate ion structure CA-[Zn(H2O)5] 2+ The minimum electrostatic potential can be attributed to the contribution of the π electron cloud on the cation accelerator molecule; and CA-[Mn(H2O)5] 2+ and CA-[Zn(H2O)5] 2+The structure has an even lower electrostatic potential minimum, further demonstrating that cation accelerators are beneficial for Mn. 2+ / Zn 2+ Ionization and deposition promote the positive electrode Mn 2+ / MnO2 and negative electrode Zn / Zn 2+ The deposition-dissolution process.

[0046] (4)Reference Figure 4 A comparison of the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in the diagram shows that the manganese hydrated ion structure coordinated in the cation accelerator is CA-[Mn(H2O)5]. 2+ The zinc hydrate ion structure CA-[Zn(H2O)5] coordinated with the cation accelerator 2+ The energy levels of the highest occupied molecular orbital (HOMO) are significantly higher than those of water-coordinated [Mn(H2O)6]. 2+ and [Zn(H2O)6] 2+ The structural values ​​are (-0.283 eV vs -0.435 eV; -0.217 eV vs -0.399 eV). Simultaneously, the manganese hydrated ion structure coordinated by the cation accelerator is CA-[Mn(H2O)5]. 2+ The zinc hydrate ion structure CA-[Zn(H2O)5] coordinated with the cation accelerator 2+ The energy level of the lowest unoccupied molecular orbital (LUMO) is significantly lower than that of water-coordinated [Mn(H2O)6]. 2+ and [Zn(H2O)6] 2+ Structure (0.015 eV vs 0.090 eV; 0.043 eV vs 0.076 eV). These results indicate that the manganese hydrated ion structure coordinated by the cation accelerator is CA-[Mn(H2O)5]. 2+ The zinc hydrate ion structure CA-[Zn(H2O)5] coordinated with the cation accelerator 2+ [Mn(H2O)6] with higher water coordination 2+ and [Zn(H2O)6] 2+ The structure facilitates redox reactions and charge transfer on the electrode surface, significantly promoting electrochemical reactions at the positive and negative electrodes of electrolytic MnO2-Zn batteries. The highest occupied molecular orbital (HOMO) refers to the highest-energy molecular orbital among electron-occupied molecular orbitals, while the lowest unoccupied molecular orbital (LUMO) refers to the lowest-energy molecular orbital among electron-unoccupied molecular orbitals.

[0047] Theoretical calculations predict that cation accelerators can promote the rapid migration of metal cations in the electrolyte system and the full transfer of charge at the electrode-electrolyte interface, thereby facilitating the growth of Mn. 2+ and Zn 2+ Electrochemical deposition / dissolution process of cations. The feasibility of the theoretical calculations is further verified below through the results of electrochemical experiments.

[0048] In some embodiments of this disclosure, based on theoretical calculations, optimized MnO2 and Zn half-cells with and without cation accelerators were assembled to verify the functionality of the cation accelerators at the positive and negative electrodes. Specific results are as follows:

[0049] Reference Figure 5 As shown, the scan rate is 10 mV / s. -1 At that time, the electrochemical stability window (ESW) test spectrum showed that the minimum electrolysis voltage range for simultaneous electrolysis of MnO2 cathode and Zn anode was about 2 V (1.07V vs -0.93V).

[0050] Reference Figure 6 Parts a and b of the diagram show a comparison of the electrochemical performance of MnO2 half-cells optimized with and without a cation exchange accelerator. The redox phases at the cathode correspond to the deposition and dissolution of MnO2. (Refer to...) Figure 7 Parts a and b of the figure show a comparison of the electrochemical performance of Zn half-cells with and without cation accelerator optimization. The redox pair at the negative electrode corresponds to the electroplating and stripping of Zn. The capacitance of the MnO2 and Zn half-cells optimized by the cation accelerator is higher than that of the half-cell without the cation accelerator due to their larger CV curve area, indicating that the cation accelerator contributes to the redox reaction of the MnO2 and Zn half-cells. With increasing scan rate, the redox peak current response of the MnO2 and Zn half-cells gradually increases, and the position of the redox peak gradually shifts to both sides of the potential window. The relationship between the redox reaction peak current and scan rate of the MnO2 and Zn half-cells with and without the cation accelerator optimization is linear, and its slope can reflect the diffusion capacity of cations in the electrolyte. The figure shows the Ig of the MnO2 and Zn half-cells optimized by the cation accelerator. O and I R The slope of the straight line is greater than that of the MnO2 half-cell and Zn half-cell without cation accelerator optimization, indicating that the cation accelerator helps to increase the Mn concentration in the electrolyte. 2+ and Zn 2+ Diffusion kinetics of cations.

[0051] Reference Figure 6As shown in section c, the cycling stability of MnO2 half-cells with and without cation accelerator optimization is compared. The MnO2 half-cell without cation accelerator optimization shows a sharp decline in capacity retention after 500 cycles in long-term cycling tests at high rates, while the MnO2 half-cell with cation accelerator optimization can cycle up to 1000 times at the same high rate and still maintain a high capacity retention.

[0052] Reference Figure 7 As shown in section c, comparing the cycle stability of Zn half-cells with and without cation accelerator optimization reveals that, at high rates, the Zn half-cell without cation accelerator optimization can only cycle for 2500 times, while the Zn half-cell with cation accelerator optimization can cycle for up to 3800 times under the same conditions.

[0053] In some embodiments of this disclosure, the aforementioned half-cells were correspondingly paired to assemble MnO2-Zn full cells with / without cation accelerators optimized, and their electrochemical performance was investigated. The test results are as follows:

[0054] Reference Figure 8 The cation-free accelerator-optimized MnO2-Zn full cell shown in section a is charged to 4 mAh cm⁻¹ at a constant voltage of 2.2 V. -2 The surface capacity, in 4 mA cm -2 (1C) to 80mAcm -2 (20 C) Discharge curves at the rate of discharge. With increasing discharge current, the discharge capacity and voltage plateau of the cation-free accelerator-optimized MnO2-Zn battery decrease significantly.

[0055] Reference Figure 8 The discharge curve of the cation accelerator-optimized MnO2-Zn battery shown in section b of the figure demonstrates a discharge performance at 4 mA / cm². -2 (1C) discharge plateau of approximately 1.95V, even at 80mA cm -2 It can maintain a smooth discharge plateau of about 1.40V at (20C), which is significantly higher than the discharge plateau of MnO2-Zn batteries without cation accelerator optimization (about 1.92V at 1C and about 1.10V at 20C).

[0056] Reference and comparison Figure 8 As shown in parts a and b, the cation accelerator-optimized MnO2-Zn battery achieves a specific capacity of up to ~455 mAh g at a high discharge rate of 20C. -1 Meanwhile, the specific capacity of the MnO2-Zn battery without cation accelerator optimization is only ~375 mAh g at a high rate of 20C. -1Compared to MnO2-Zn batteries optimized by a cation accelerator, MnO2-Zn batteries without a cation accelerator have a specific capacity that is approximately 80 mAh g lower. -1 .

[0057] Reference Figure 9 As shown in the comparison graph of rate performance of MnO2-Zn batteries with and without cation accelerator optimization, the coulombic efficiency, discharge plateau, and discharge capacity of the MnO2-Zn battery with cation accelerator optimization are significantly improved compared with the MnO2-Zn battery without cation accelerator optimization.

[0058] Reference Figure 10 The cation accelerator-optimized MnO2-Zn battery shown exhibits excellent cycling performance even at high rates of 20C.

[0059] (1) The MnO2-Zn aqueous battery optimized by the cation accelerator at 80 mA / cm² -2 After cycling 2000 times at a given current density, the energy density can be stably maintained at 50 Wh / m³. -2 Around 40 Wh / m³. Meanwhile, the energy density of MnO₂-Zn batteries without cation accelerator optimization only maintains approximately 40 Wh / m³ after 100 cycles. -2 It also decays rapidly after 750 cycles.

[0060] (2) Compared with the cation-accelerator-free MnO2-Zn aqueous battery, the cation-accelerator-optimized MnO2-Zn aqueous battery showed significantly improved discharge plateau and discharge capacity in the first cycle. From 100 to 700 cycles, the discharge plateau of the MnO2-Zn aqueous battery decayed faster than that of the cation-accelerator-optimized MnO2-Zn battery. The discharge voltage plateau of the cation-accelerator-free MnO2-Zn aqueous battery decayed to ~1V after 850 cycles, while the cation-accelerator-optimized MnO2-Zn aqueous battery maintained a discharge plateau of ~1.25V even after 2000 cycles.

[0061] (3) The MnO2-Zn aqueous battery optimized by the cation accelerator maintained high energy efficiency and long-term cycle stability at high discharge rates, highlighting the advantages of the cation accelerator strategy.

[0062] In some embodiments of this disclosure, the concentration range of anions in the electrolyte system includes 0.001 mol / L to 10 mol / L.

[0063] In some embodiments of this disclosure, Mn in the electrolyte system 2+ The concentration range of Zn ions is 0.001 mol / L to 10 mol / L. 2+The concentration range of the ions includes 0.001 mol / L to 10 mol / L, H+ + The concentration range of ions is from 0.0001 mol / L to 1 mol / L.

[0064] In some embodiments of this disclosure, the pH value of the electrolyte system is 0.1 to 2.

[0065] In some embodiments of this disclosure, the electrolytic MnO2-Zn aqueous battery does not use any separator, and the electrolyte system used is a single-liquid battery system, which can completely avoid the influence of the separator's conductivity on the performance of the electrolytic MnO2-Zn aqueous battery.

[0066] The embodiments of this disclosure provide a cation accelerator-optimized electrolytic MnO2-Zn aqueous battery. By employing a cation accelerator, the electrolytic reaction kinetics of both the MnO2 cathode and Zn anode are simultaneously promoted, significantly improving the electrochemical performance of the electrolytic MnO2-Zn aqueous battery. Through a combination of theoretical guidance and experimental verification (i.e., using polyvinylpyrrolidone (PVP) as a model cation accelerator based on theoretical calculations), the cation accelerator-optimized electrolytic MnO2-Zn aqueous battery is assembled. This leverages the function of the cation accelerator to accelerate the migration of metal cations in the electrolyte system and promote sufficient charge transfer at the electrode-electrolyte interface, thereby promoting the electrolytic reaction of MnO2-Zn ... 2+ / Zn 2+ The deposition and dissolution process of metal cations enables highly reversible and long-term cycling of electrolytic MnO2-Zn aqueous batteries at high rates. The electrode and electrolyte systems of the cation-accelerator-optimized electrolytic MnO2-Zn aqueous batteries utilize low-cost materials. The battery assembly process eliminates the need for a separator, avoiding side reactions associated with separators and significantly reducing battery costs. Furthermore, the electrolyte system of the cation-accelerator-optimized electrolytic MnO2-Zn aqueous batteries is a non-flammable and highly safe aqueous electrolyte system, which significantly improves battery safety. In addition, the electrolytic MnO2-Zn aqueous batteries provided in the embodiments of this disclosure are simple to assemble, low in cost, easily reproducible, and readily scalable for industrial-scale production.

[0067] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A cation accelerator-optimized electrolytic MnO2-Zn aqueous battery, characterized in that, include: Positive electrode made of MnO2; Negative electrode made of Zn; An electrolyte system, wherein the electrolyte system is an acidic solution containing metal cations, and the pH value of the electrolyte system is 0.1~2; wherein the metal cations include at least Mn. 2+ Zn 2+ ; A cation accelerator, through interaction with the metal cation Mn 2+ or Zn 2+ Water molecules form a hydrated ionic structure, regulating the metal cation Mn 2+ Zn 2+ The solvation structure promotes the metal cation Mn 2+ Zn 2+ The deposition and dissolution processes; The cation accelerator and the metal cation Mn 2+ A manganese complex is formed, and the manganese complex coordinates with H2O molecules to form a cation accelerator coordinated manganese hydrated ion structure; The cation accelerator and the metal cation Zn 2+ A zinc complex is formed, and the zinc complex coordinates with H2O molecules to form a zinc hydrated ion structure coordinated with a cation accelerator. The cation accelerator includes any one of polyvinyl alcohol, dimethyl sulfoxide, and polyvinylpyrrolidone.

2. The electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator according to claim 1, characterized in that, The concentration range of the cation accelerator in the electrolyte system includes 0.001 mmol / L to 0.1 mmol / L.

3. The electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator according to claim 1, characterized in that, The electrolyte system is a single-liquid battery system.

4. The electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator according to claim 1, characterized in that, The highest occupied molecular orbital energy level of the manganese hydrated ion structure coordinated by the cation accelerator is higher than that of [Mn(H2O)6). 2+ The energy level of the highest occupied molecular orbital; The highest occupied molecular orbital energy level of the zinc hydrate ion structure coordinated by the cation accelerator is higher than that of [Zn(H2O)6). 2+ The energy level of the highest occupied molecular orbital.

5. The electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator according to claim 1, characterized in that, The lowest unoccupied molecular orbital of the manganese hydrated ion structure coordinated by the cation accelerator has an energy level lower than [Mn(H2O)6). 2+ The lowest unoccupied molecular orbital energy level; The lowest unoccupied molecular orbital of the zinc hydrate ion structure coordinated by the cation accelerator has an energy level lower than [Zn(H₂O)₆). 2+ The lowest unoccupied molecular orbital energy level.

6. The electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator according to claim 1, characterized in that, The desolvation energy of the manganese hydrated ion structure coordinated in the cation accelerator is lower than that of [Mn(H₂O)₆]. 2+ Desolvation energy; The desolvation energy of the zinc hydrate ion structure coordinated by the cation accelerator is lower than that of [Zn(H₂O)₆]. 2+ Desolvation energy.

7. The electrolytic MnO2-Zn aqueous battery optimized by a cation accelerator according to claim 1, characterized in that, Mn in the electrolyte system 2+ The concentration range of the ions includes 0.001 mol / L to 10 mol / L, Zn 2+ The concentration range of the ions is 0.001 mol / L to 10 mol / L.

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