Single-ion polymer electrolyte membrane based on sulfonated graphene oxide as well as preparation method and application thereof

Abstract

The invention discloses a single-ion polymer electrolyte membrane based on sulfonated graphene oxide as well as a preparation method and application thereof and belongs to the technical field of electrochemistry. The membrane disclosed by the invention has uniform and compact pore structure distribution, the porosity is 55-57%, the liquid absorption rate of the diaphragm is 138-141%, and pores arecommunicated with one another in the membrane, so that the establishment of a lithium ion transmission channel is facilitated. According to the invention, the sulfonated graphene oxide is doped intoa single-ion polymer electrolyte taking wholly aromatic polyamide as a framework support by adopting an in-situ polymerization method, so that the ionic conductivity of the electrolyte can be improved. The membrane disclosed by the invention is applied to a LiFePO4 half-cell, and the membrane shows good rate capability at room temperature: the specific discharge capacity at 0.1 C rate reaches 143mAh.G<-1>, the specific discharge capacity is hardly attenuated after 60 circles of charging and discharging at 1C, and the electrochemical performance is excellent.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and in particular relates to a single-ion polymer electrolyte diaphragm based on sulfonated graphene oxide and its preparation method and application. Background technique [0002] At present, the commercial polymer electrolyte is composed of microporous polyolefin separator / liquid electrolyte system, but the system still has the following major disadvantages: (1) The low glass transition temperature and low melting point of polyolefin make the system Under high temperature conditions, the shrinkage is severe. Once the temperature is too high, it will cause a short circuit inside the battery, resulting in fire or even explosion; (2) The pore structure of the polyolefin separator is produced by the stretching process. In order to ensure the high mechanical strength of the separator, the porosity is usually If it is less than 50%, it is not conducive to the adsorption and retention of the ...

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Problems solved by technology

[0002] At present, the commercial polymer electrolyte is composed of microporous polyolefin separator / liquid electrolyte system, but the system still has the following major disadvantages: (1) The low glass transition temperature and low melting point of polyolefin make the system Under high temperature conditions, the shrinkage is severe. Once the temperature is too high, it will cause a short circuit inside the battery, resulting in fire or even explosion; (2) The pore structure of the polyolefin separator is produced by the stretching process. In order to ensure the high mechanical strength of the separator, the porosity is usually If it is less than 50%, it is not conducive to the adsorption and retention of the electrolyte, which affects the performance of the battery; (3) the non-polar characteristics of the polyolefin separator have poor compatibility with polar organic solvents, resulting in poor electrolyte wettability; (4) LiPF 6 The thermal instability (>60°C) and moisture sensitivity (>10ppm) of lithium salts make the system unable to work at high temperature and aqueous atmosphere; (5) LiPF 6 The low lithium ion migration number leads to a large lithium salt concentration gradient at high charge / discharge rates, which is prone to lithium dendrites and limits power delivery.

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