Sulfonated graphene oxide-based single-ion polymer electrolyte separator and its preparation method and application

Abstract

The invention discloses a single-ion polymer electrolyte diaphragm based on sulfonated graphene oxide, a preparation method and application thereof, and belongs to the technical field of electrochemistry. The membrane of the present invention has a uniform and dense pore structure distribution, the porosity is 55-57%, the liquid absorption rate of the membrane is 138-141%, and these pores are interconnected inside the membrane, which is beneficial to the transmission of lithium ions Channel establishment. The invention adopts the in-situ polymerization method to incorporate the sulfonated graphene oxide into the single-ion polymer electrolyte supported by the all-aromatic polyamide as the skeleton, so as to improve the ion conductivity of the electrolyte. Applying the separator of the present invention to LiFePO 4 In the half-cell, the system exhibits good rate performance at room temperature: the discharge specific capacity reaches 143mAh g at 0.1C rate ‑1 , under 1C charging and discharging for 60 cycles, the specific capacity has almost no attenuation, 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 membrane based on sulfonated graphene oxide and a preparation method and application thereof. Background technique [0002] At present, commercial polymer electrolytes are composed of microporous polyolefin separator / liquid electrolyte system, but this system still has the following main disadvantages: (1) The low glass transition temperature and low melting point of polyolefin make the system in The shrinkage is severe under high temperature conditions. 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 Below 50%, it is not conducive to the adsorption and retention of the electrol...

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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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