CN-122025667-A - HNBR modified positive electrode plate, positive electrode current collector, diaphragm and lithium-air battery

Abstract

The invention discloses an HNBR modified positive electrode plate, a positive electrode current collector, a diaphragm and a lithium-air battery. The HNBR modified positive electrode plate is obtained by soaking a positive electrode plate for a lithium-air battery with HNBR glue solution and drying. The HNBR modified positive current collector is characterized in that a layer of HNBR coating is formed on the surface of a positive current collector for a lithium-air battery, and the load capacity of the HNBR coating is 0.2-0.5 mg/cm 2 . The HNBR modified diaphragm is formed by coating a layer of composite coating of HNBR and hydrophobic polymer on one side of a diaphragm for a lithium-air battery facing to a positive electrode, wherein the mass ratio of HNBR to hydrophobic polymer is 1:1-1:5. The present invention provides a lithium-air battery thus obtained. The invention can improve the cycling stability of the lithium-air battery and reduce the first-cycle passing potential through HNBR modification.

Inventors

• ZHAN ZHENGYUN

Assignees

• 上海赞南科技股份有限公司
• 浙江赞昇新材料有限公司

Dates

Publication Date

20260512

Application Date

20260306

Claims (10)

1. 1. The HNBR modified positive electrode plate for the lithium-air battery is characterized by being obtained by soaking the positive electrode plate for the lithium-air battery with HNBR glue solution with the concentration of 0.25-1 mg/mL and then drying.
2. 2. The HNBR modified positive electrode sheet for a lithium-air battery as recited in claim 1, wherein the concentration of the HNBR dope is 0.5 to 0.75 mg/mL.
3. 3. A lithium-air battery comprises a positive electrode plate and is characterized in that the positive electrode plate is the HNBR modified positive electrode plate in claim 1 or 2.
4. 4. The HNBR modified positive electrode current collector for the lithium-air battery is characterized in that a layer of HNBR coating is formed on the surface of the positive electrode current collector for the lithium-air battery, and the loading capacity of the HNBR coating is 0.2-0.5 mg/cm 2 .
5. 5. The HNBR modified positive electrode current collector for a lithium-air battery as in claim 4 wherein the positive electrode current collector for a lithium-air battery is carbon paper and the loading of the HNBR coating in the HNBR modified positive electrode current collector is 0.2 to 0.4mg/cm 2 .
6. 6. A lithium-air battery comprising a positive electrode current collector, wherein the positive electrode current collector is the HNBR modified positive electrode current collector as claimed in claim 4 or 5.
7. 7. The HNBR modified diaphragm for the lithium-air battery is characterized in that a layer of composite coating of HNBR and hydrophobic polymer is coated on the side, facing to a positive electrode, of the diaphragm for the lithium-air battery, wherein the mass ratio of HNBR to hydrophobic polymer is 1:1-1:5.
8. 8. The HNBR modified separator for a lithium-air battery according to claim 7, wherein said hydrophobic polymer is at least one of poly (trifluoroethyl methacrylate), poly (2- (perfluorohexyl) ethyl acrylate), polytetrafluoroethylene, and polysiloxane.
9. 9. The HNBR modified separator for a lithium-air battery of claim 7 wherein the loading of the composite coating of HNBR and hydrophobic polymer is from 0.005 to 0.01 mg/cm 2 .
10. 10. A lithium-air battery comprising a separator, wherein the separator is a HNBR modified separator according to any one of claims 7 to 9, and wherein a side of the separator containing a composite coating layer of HNBR and a hydrophobic polymer faces a positive electrode.

Description

HNBR modified positive electrode plate, positive electrode current collector, diaphragm and lithium-air battery Technical Field The invention belongs to the technical field of new energy materials, and particularly relates to an HNBR (hydrogenated nitrile butadiene rubber) modified positive electrode plate for a lithium-air battery, a positive electrode current collector, a diaphragm and the lithium-air battery. Background The theoretical energy density (3500 Wh/kg) of the lithium-air battery is far beyond that of the lithium ion battery, and the lithium-air battery is regarded as a candidate technology of a next-generation high-energy storage system. However, the development of lithium-air batteries still faces many challenges. The positive electrode side of the lithium-air battery needs to consider the simultaneous transfer of electrons, ions and gaseous reactants at the three-phase interface of the gas (O 2) -electrolyte-solid electrode, which is essentially different from the two-phase reaction interface of the electrolyte-solid electrode in the lithium-ion battery. Therefore, multi-stage pore designs, namely macroscopic pore (O 2 diffusion), mesoscopic pore (electrolyte infiltration) and micropore (catalytic site exposure), are required in the construction of lithium-air battery electrodes, which place higher demands on the electrode structural design. The polymer material plays an extremely important role in the construction of the lithium-air battery electrode, and determines the stability and the function of the microstructure of the electrode to a great extent. the main function of the adhesive comprises ① adhesive for maintaining active substances (such as conductive agent, Catalyst) and a current collector to prevent active substances from falling off, ② modifier, wherein a gas diffusion layer can be formed on the surface of the modified electrode to promote O 2 to diffuse to a reaction interface and prevent flooding caused by electrolyte permeation, ③ ion diffusion, adsorption of Li + to form a rapid ion channel to improve the migration number of Li + and reduce concentration polarization, ④ auxiliary catalysis, promotion of O 2 adsorption activation and acceleration of reaction kinetics, regulation of morphology of a discharge product, induction of Li 2O2 to grow in a film shape instead of a particle shape, reduction of decomposition overpotential, ⑤ interface protection, and coating of an insulating polymer on the surface of carbon can block side reaction of carbon and Li 2O2 and reduce the generation of byproducts such as lithium carbonate. Currently, polyvinylidene fluoride (PVDF) is a commonly used polymeric material in lithium-air batteries, but has some limitations. For example, PVDF is easy to undergo defluorination reaction in a strong oxidizing environment to generate acidic byproducts such as HF and the like, so that electrolyte decomposition is accelerated to cause cycle capacity attenuation, and secondly, repeated volume changes of PVDF in the cycle process can cause electrode cracking (such as stress caused by Li 2O2 deposition/stripping) to destroy a conductive network. With the increasingly strict environmental protection requirements and the continuous improvement of battery performance requirements, the search for a polymer material with more environmental protection, more excellent performance and new functions becomes a research hotspot. Disclosure of Invention The invention provides an HNBR (hydrogenated nitrile rubber) modified positive electrode plate, a positive electrode current collector, a diaphragm and a lithium-air battery for the lithium-air battery, which are modified by HNBR to improve the cycle stability of the lithium-air battery and reduce the first-cycle overpotential. In a first aspect, the invention provides an HNBR modified positive electrode plate for a lithium-air battery, which is obtained by soaking the positive electrode plate for the lithium-air battery with HNBR glue solution with the concentration of 0.25-1 mg/mL and then drying. In some embodiments, the HNBR has an ACN mass content of 18% to 41%, a hydrogenation saturation of >99%, a Mooney viscosity value ML (1+4) @100 ℃ of 19-60 when the HNBR is a solid, and a molecular weight Mw of 15,000-25,000 when the HNBR is a liquid (the Mooney viscosity value of which cannot be measured). The positive electrode sheet conventionally used for the lithium-air battery includes a positive electrode current collector, and a catalyst and a binder supported on the surface of the positive electrode current collector. The positive electrode current collector may be carbon paper (hydrophobic or hydrophilic carbon paper), foam nickel, ketjen black, acetylene black, carbon Nanotubes (CNTs), or the like. The catalyst may be noble metal platinum, gold, palladium, ruthenium, transition metal oxide (Co 3O4、MnO2), etc., preferably nano platinum. The binder is used to bind the catalyst to the positive current collector