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CN-115101768-B - Electrolytic MnO2Zn water-based battery

CN115101768BCN 115101768 BCN115101768 BCN 115101768BCN-115101768-B

Abstract

The invention provides an electrolytic MnO 2 -Zn water system battery optimized by a cation accelerator, which comprises an anode, a cathode, an electrolyte system and a cation accelerator, wherein the anode is MnO 2 , the cathode is Zn, the electrolyte system is an acidic solution containing metal cations, the metal cations at least comprise Mn 2+ 、Zn 2+ at the same time, the cation accelerator adjusts a solvation structure of the metal cations Mn 2+ 、Zn 2+ by forming a hydrated ion structure with the metal cations Mn 2+ or Zn 2+ and water molecules, promotes the deposition and dissolution processes of the metal cations Mn 2+ 、Zn 2+ , and improves the electrochemical performance of the electrolytic MnO 2 -Zn water system battery.

Inventors

  • CHEN WEI
  • CHUAI MINGYAN
  • YUAN YUAN

Assignees

  • 中国科学技术大学

Dates

Publication Date
20260512
Application Date
20220623

Claims (7)

  1. 1. A cation accelerator optimized electrolytic MnO 2 -Zn water-based battery comprising: A positive electrode made of MnO 2 ; A negative electrode made of Zn; 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 at least comprise Mn 2+ 、Zn 2+ at the same time; A cation accelerator, which adjusts the solvation structure of the metal cation Mn 2+ 、Zn 2+ by forming a hydrated ion structure with the metal cation Mn 2+ or Zn 2+ and water molecules, and promotes the deposition and dissolution process of the metal cation Mn 2+ 、Zn 2+ ; the cation accelerator forms a manganese complex with the metal cation Mn 2+ , and the manganese complex coordinates with the H 2 O molecule to form a cation accelerator coordinated manganese hydrated ion structure; The cation accelerator forms a zinc complex with the metal cation Zn 2+ , and the zinc complex coordinates with the H 2 O molecule to form a cation accelerator coordinated zinc hydrated ion structure; Wherein the cation accelerator comprises any one of polyvinyl alcohol, dimethyl sulfoxide and polyvinylpyrrolidone.
  2. 2. The cation accelerator optimized electrolytic MnO 2 -Zn aqueous cell of claim 1, The concentration range of the cation accelerator in the electrolyte system comprises 0.001 mmol/L-0.1 mmol/L.
  3. 3. The cation accelerator optimized electrolytic MnO 2 -Zn aqueous cell of claim 1, The electrolyte system is a single-liquid battery system.
  4. 4. The cation accelerator optimized electrolytic MnO 2 -Zn aqueous cell of claim 1, The highest occupied molecular orbital of the manganese hydrated ion structure coordinated by the cation accelerator is higher than the energy level of [ Mn (the highest occupied molecular orbital of H 2 O) 6 )] 2+ ; The highest occupied molecular orbital of the zinc hydrated ion structure coordinated by the cation accelerator is higher than [ Zn (the highest occupied molecular orbital of H 2 O) 6 )] 2+ ).
  5. 5. The cation accelerator optimized electrolytic MnO 2 -Zn aqueous cell of claim 1, The cation accelerator coordinates manganese hydrous ion structure having a lowest unoccupied molecular orbital energy level lower than [ Mn (energy level of lowest unoccupied molecular orbital of H 2 O) 6 )] 2+ ; the lowest unoccupied molecular orbital of the zinc hydrated ion structure coordinated by the cation accelerator is lower in energy level than [ Zn (the energy level of the lowest unoccupied molecular orbital of H 2 O) 6 )] 2+ ).
  6. 6. The cation accelerator optimized electrolytic MnO 2 -Zn aqueous cell of claim 1, The cation accelerator coordinates a manganese hydrous ion structure having a desolvation energy lower than [ Mn (desolvation energy of H 2 O) 6 )] 2+ ; The cation accelerator coordinates zinc hydrous ion structure with a desolvation energy lower than [ Zn (desolvation energy of H 2 O) 6 )] 2+ ).
  7. 7. The cation accelerator optimized electrolytic MnO 2 -Zn aqueous cell of claim 1, The concentration range of Mn 2+ ions in the electrolyte system is 0.001 mol/L-10 mol/L, and the concentration range of Zn 2+ ions is 0.001 mol/L-10 mol/L.

Description

Electrolytic MnO 2 -Zn water system battery Technical Field The disclosure relates to the technical field of energy storage of water-based zinc-manganese batteries, in particular to an electrolytic MnO 2 -Zn water-based battery. Background Excessive consumption of fossil fuels and excessive emission of carbon dioxide (CO 2) greenhouse gases cause serious energy crisis and environmental pollution problems. Rational development and utilization of new clean renewable energy sources is particularly important for human sustainable development. Clean energy sources such as wind energy, solar energy and the like have randomness and indirection and are difficult to directly incorporate into a power grid, so that a large-scale energy storage technology needs to be developed to realize time shifting of electric energy so as to meet random electricity utilization requirements of a user side. Although typical lithium ion batteries have high energy density and power density and are commercially used for decades, the use of flammable organic electrolyte has limited their development in large-scale energy storage applications. Therefore, it is important to develop a high-safety and low-cost aqueous battery. Among the numerous aqueous batteries, electrolytic MnO 2 -Zn batteries are attracting attention because of their advantages of low cost, high output voltage, high safety, environmental friendliness, etc., and are expected to be applied in the field of large-scale energy storage. Unlike conventional aqueous zinc-manganese batteries based on MnO 2 positive single electron transfer reactions, electrolytic MnO 2 -Zn batteries are mainly based on solid/liquid phase reactions of positive (MnO 2/Mn2+) and negative (Zn/Zn 2+) double electron transfer. The advantages of the electrolytic MnO 2 -Zn cell are mainly represented by the fact that the reversible MnO 2/Mn2+ positive electrode deposition/dissolution reaction has a suitable redox potential of 1.23V vs SHE and a high theoretical specific capacity of 616mAh g -1, while the reversible Zn/Zn 2+ negative electrode deposition/dissolution reaction has a low redox potential of-0.76V vs SHE and a high theoretical specific capacity of 820mAh g -1. The low-cost MnO 2 anode and the Zn cathode are matched, so that the ideal water-based battery with low cost and high energy density can be assembled. However, the development of MnO 2 -Zn cells is still hampered by problems such as low energy density, poor reversibility of electrode reactions, slow solid state charge storage reactions, large overpotential due to electrochemical polarization, ion intercalation, and tilting of voltage curves due to phase change processes. In particular, the slow reaction kinetics of the positive electrode (MnO 2/Mn2+) lead to MnO 2 -Zn cells with lower energy efficiency (< 50%) at high rates. Particularly at larger deposition capacities, slow deposition/dissolution reactions tend to result in a gradual accumulation of inactive materials of the positive and negative electrodes, forming "dead MnO 2" and "dead Zn", thereby significantly compromising the cycle life of the MnO 2 -Zn cell. In order to enhance the reaction kinetics of MnO 2 -Zn batteries, various methods applied to the positive electrode of the battery have been explored, including preparing materials with porous structures, constructing ion and electron conductive frameworks, embedding conductive polyaniline and phosphate ions, introducing pseudocapacitance, regulating oxygen vacancies or nitrogen doping, and the like. Various strategies to cope with Zn negative electrode problems have also been studied, such as developing new three-dimensional electrodes, surface coating techniques, water-in-salt electrolytes, electrolyte additives, etc. However, the overall electrochemical performance of MnO 2 -Zn cells cannot be fully developed by unilaterally improving the deposition/dissolution chemistry of MnO 2/Mn2+ positive electrode or unilaterally improving the plating/stripping reaction of Zn/Zn 2+ negative electrode. Therefore, the present disclosure designs a scheme of a cation accelerator to simultaneously promote the reaction kinetics of the positive electrode and the negative electrode and sufficiently improve the overall performance of the electrolytic MnO 2 -Zn battery. Disclosure of Invention To at least partially address at least one of the above-mentioned technical drawbacks, embodiments of the present disclosure provide a cation accelerator optimized electrolytic MnO 2 -Zn water-based battery, wherein the cation accelerator forms a hydrated ion structure coordinated with the metal cation Mn 2+ or Zn 2+, and water molecules, adjusts the solvation structure of the metal cation Mn 2+、Zn2+, promotes the deposition and dissolution process of the metal cation Mn 2+、Zn2+, and improves the electrochemical performance of the electrolytic MnO 2 -Zn water-based battery. In order to achieve the above object, as an embodiment of one aspect of the prese