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CN-122000376-A - Zinc-based flow battery structure

CN122000376ACN 122000376 ACN122000376 ACN 122000376ACN-122000376-A

Abstract

The invention relates to a zinc-based flow battery, which comprises a positive electrode current collector, a diaphragm and a negative electrode current collector which are sequentially overlapped, wherein a gap is reserved between the positive electrode current collector and the diaphragm, and a gap is reserved between the diaphragm and the negative electrode current collector, so that the positive and negative electrode sides of the diaphragm are of cavity structures, namely a positive electrode cavity and a negative electrode cavity. The electrode spacing of the battery is reduced while the surface capacity and the shelf performance of the battery are ensured, and the performance of the battery is further improved.

Inventors

  • XU PENGCHENG
  • LI XIANFENG
  • YUAN ZHIZHANG

Assignees

  • 中国科学院大连化学物理研究所

Dates

Publication Date
20260508
Application Date
20241101

Claims (9)

  1. 1. The utility model provides a zinc-based flow battery structure, includes positive pole current collector, diaphragm, the negative pole current collector of coincide in proper order, its characterized in that: A gap is reserved between the positive electrode current collector and the diaphragm, and a gap is reserved between the diaphragm and the negative electrode current collector, so that the positive side and the negative side of the diaphragm are of cavity structures, namely a positive electrode cavity and a negative electrode cavity.
  2. 2. The zinc-based flow battery structure of claim 1, wherein: The gap between the positive electrode current collector and the diaphragm is internally provided with a positive electrode, and the gap between the diaphragm and the negative electrode current collector is internally provided with a negative electrode, so that the zinc-based flow battery structure is formed into a zinc-based flow battery structure without the positive electrode and the negative electrode; The intervals between the positive electrode current collector and the diaphragm and between the diaphragm and the negative electrode current collector are respectively realized through a hollow annular gasket or a hollow annular electrode frame; The gap between the positive electrode current collector and the diaphragm is used as a chamber for accommodating positive electrode electrolyte, and the gap between the diaphragm and the negative electrode current collector is used as a chamber for accommodating positive electrode electrolyte.
  3. 3. The zinc-based flow battery structure of claim 1, wherein: The thickness of the positive electrode cavity (the distance between the positive electrode current collector and the separator) is 0.5-2mm, preferably 0.5-1mm, and more preferably 0.5-0.8mm.
  4. 4. The zinc-based flow battery structure of claim 1, wherein: the negative electrode cavity thickness (distance between the negative electrode current collector and the separator) is 0.5-3mm, preferably 2-2.5mm, and more preferably 2.3-2.5mm.
  5. 5. The zinc-based flow battery structure of claim 1, 3 or 4, wherein: And a carbon powder layer is sprayed on the surface of the positive electrode side current collector of the zinc-based flow battery, which faces the diaphragm.
  6. 6. The zinc-based flow battery structure of claim 5, wherein: The carbon powder is a mixture of expanded graphite and activated carbon, wherein the mass ratio of the expanded graphite to the activated carbon is 1:2-2:1, preferably 1:1-1.2.
  7. 7. The zinc-based flow battery structure of claim 5, wherein: The sprayed carbon powder layer also contains a binder, wherein the binder is one or two of polyvinylidene fluoride (PVDF) and Nafion, and preferably Nafion; The mass ratio of carbon powder to binder in the spraying slurry is 8:1-10:1, preferably 8.5-9:1.
  8. 8. The zinc-based flow battery structure according to claim 5, wherein the carbon powder loading on the surface of the positive electrode side electrode is 4-12mg/cm 2 , preferably 8-10mg/cm 2 , and more preferably 9-10mg/cm 2 .
  9. 9. The zinc-based flow battery structure according to claim 1,3 or 4, wherein the surface roughness Ra of the separator-facing side of the negative electrode current collector is in the range of 60 to 100um, preferably 80 to 100um, and more preferably 85 to 90um.

Description

Zinc-based flow battery structure Technical Field The invention relates to the technical field of flow batteries, in particular to the field of zinc-based flow batteries. Background Renewable energy sources such as wind energy and solar energy have the characteristics of discontinuity and instability, and the characteristic can cause impact on a power grid in the grid connection process, so that the safe and stable operation of the power grid is affected. The energy storage technology can ensure the high-efficiency stable operation of the renewable energy power generation grid connection. The energy storage technology is mainly divided into two main types of physical energy storage and chemical energy storage. Redox flow batteries suitable for large-scale and large-capacity energy storage in chemical energy storage are receiving attention because of the advantages of independent battery power and capacity, rapid response, simple structure, easy design and the like. Among them, zinc-based flow batteries are receiving a great deal of attention because of their high energy density, abundant raw material reserves, and low price. The zinc-based flow battery mainly comprises a zinc bromine flow battery, a zinc-iron flow battery, a zinc-iodine flow battery, a zinc-nickel flow battery and the like, and the negative electrode of the zinc-based flow battery is subjected to deposition dissolution reaction of metallic zinc in the charging and discharging processes of the battery. In addition, in order to obtain higher working current density, the anode and cathode electrode materials of the zinc-based flow battery generally adopt carbon felts, graphite felts and the like as electrode materials, and the carbon felts can absorb certain electrolyte, so that the zinc corrosion problem exists in the zinc-based battery in the shelving process, and the zinc corrosion reactions of the alkaline and acidic zinc-based flow batteries are respectively as follows: Zn―2e―+4OH―→ZnO+H2O The zinc corrosion problem can lead to reduced discharge capacity of the zinc-based battery after the zinc-based battery is placed on the shelf, and the overall efficiency of the battery is affected. In addition, the use of electrode materials such as carbon felt, graphite felt and the like further increases the manufacturing cost of the zinc-based flow battery. In the patent (CN 202211549404.7), the structural design of the cavity is adopted at the negative electrode side, so that the surface capacity of the zinc-based flow battery is improved, the corrosion of zinc is reduced, and the battery shelving performance is improved. However, the positive electrode side of the structure still needs to use a carbon felt, and at the same time, a support needs to be added to the surface of the electrode frame on the negative electrode side, which is close to the separator side, so that the contact resistance of the positive electrode under the structure is reduced, which increases the manufacturing cost of the battery. In addition, when the carbon felt is adopted as the electrode of the flow battery, an electrolyte dead zone is formed on the electrode, namely the flow rate of the electrolyte in the area is very slow, mass transfer in the electrochemical reaction process is influenced, the area resistance is higher, the charging voltage in the area is high, the discharging voltage is low, the performance of the electric pile is reduced, and the long-term circulating operation can also cause penetration of the electrode, so that the electric pile is invalid. Disclosure of Invention According to the zinc-based flow battery structure, the positive electrode and the negative electrode adopt a cavity structure mode, so that the battery surface capacity and the shelving performance are ensured, the electrode distance of the battery is reduced, and the battery performance is further improved. The zinc-based flow battery structure component comprises an end plate, a positive current collector, a diaphragm, a negative current collector and an end plate which are sequentially overlapped. The zinc-based flow battery structure is a cavity structure on both the positive side and the negative side. And a certain amount of carbon powder is sprayed on the surface of the current collector on the positive electrode side of the zinc-based flow battery in a spraying mode. The carbon powder in the spraying slurry is expanded graphite and activated carbon, wherein the mass ratio of the expanded graphite to the activated carbon is 1:2-2:1, and preferably 1:1. The binder in the spraying slurry is one of polyvinylidene fluoride (PVDF) or Nafion solution, preferably Nafion solution. The mass ratio of carbon powder to binder in the spraying slurry is 8:1-10:1, preferably 9:1. The carbon powder loading on the surface of the positive electrode side electrode is 4-12mg/cm 2, preferably 8-10mg/cm 2, and more preferably 10mg/cm 2. The positive electrode cavity thickness is 0.5-2mm, preferably 0