| Rechargeable Lithium-ion batteries (LIBs) have great energy and power density, high working voltage, long cycle life, no memory effect, good safety performance and fast-charging capability, etc., thus they will have become the new power source technology research hotspot in recent years. The separator is a critical component in LIBs and is placed between the positive electrode and the negative electrode to prevent physical contact of the electrodes while enabling free ionic transport and isolating electronic flow. The separator performance quality which determines the battery interface structure, internal resistance etc., directly affects the battery capacity, cycling performance and safety properties and other characteristics. The separator with excellent properties plays a key role in improving the comprehensive performance of the battery.This paper is mainly about the study on using the electrospinning technique to prepare and modified separator materials for the advanced lithium-ion batteries(LIBs), including the following aspects:(1) Electrospinning technique is combined with the high temperature solid-state reaction method and the sol-gel method to prepare the perovskite-type lithium fast ion conductor ceramic nano material lithium-lanthanum -titanate oxide (LLTO); (2) The research on the fabrication and electrochemical characterization of the electrospinning LLTO/PAN composite fibrous membrane for lithium-ion battery separator; (3) The research on the fabrication and electrochemical characterization of the electrospinning LATP/PAN composite fibrous membrane forlithium-ion battery separator; (4) The research on the modification of the Celgared 2400 polypropylene microporous membrane by the electrospun PVDF nanofibers.Two methods (the electrospinning technique combined with high temperature solid-state reaction, the sol-gel method) were used to prepare the perovskite-type lithium fast ion conductor ceramic nanoparticles lithium lanthanum titanate oxide (LLTO). The crystal structure, morphology, and the ionic conductivity of the perovskite-type lithium fast ion conductor ceramic nanoparticles lithium lanthanum titanate oxide (LLTO) which was prepared by these two methods were characterized and measured. The results demonstrated that the samples prepared by the sol-gel method can get relatively pure crystalline phase and have uniform particle size, slight agglomeration and relatively high ionic conductivity.The electrospinning technique was used to prepare the LLTO/PAN composite fiber membrane with different lithium lanthanum titanate oxide (LLTO) content (0%,5%,10% and 15%). The electrolyte uptake of the electrospun LLTO/PAN composite fiber membranes was tested and found that with an increase of the perovskite-type lithium fast ion conductor ceramic nano material lithium lanthanum titanate oxide (LLTO) content, the electrolyte uptake of the electrospun LLTO/PAN composite fiber membranes slightly increased. When the lithium ion conductivity, the electrochemical stability window and the interface resistance of the electrolyte-soaked electrospun LLTO/PAN composite fiber membrane were tested, it was found that as the perovskite-type lithium fast ion conductor ceramic nano material lithium lanthanum titanate oxide LLTO content increased, the electrospun LLTO/PAN composite fiber-based membranes had higher lithium ion conductivity, higher electrochemical stability window, and lower interfacial resistance with lithium electrode. In addition, lithium//1 M LiPF6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes used as the separator have exhibited good charge/discharge capacity and cycle performance.Using the sol-gel method to prepare the NASICON-type lithium fast ion conductor ceramic nanoparticles lithium aluminum titanium phosphate (LATP).The electrospinning technique was used to prepare the LATP/PAN composite fiber membrane with different LATP content (0%,5%,10% and 15%). The electrolyte uptake of the electrospun LATP/PAN composite fiber membranes was tested and the results showed as the NASICON-type lithium fast ion conductor ceramic nano material lithium aluminum titanium phosphate (LATP) content increase, the electrolyte uptake of electrospun LATP/PAN composite fiber membranes slightly increase. The lithium ion conductivity, the electrochemical stability window and the interface resistance of the electrolyte-soaked electrospun LATP/PAN composite fiber membrane were also measured and the consequence exhibited that as the NASICON-type lithium fast ion conductor ceramic nano material lithium aluminum titanium phosphate (LATP) content increase, the electrospun LATP/PAN composite fiber-based membranes had higher lithium ion conductivity, higher electrochemical stability window, and lower interfacial resistance with lithium electrode. Additionally, lithium//1 M LiPF6/EC/EMC//lithium iron phosphate cells including LATP/PAN composite fiber-based membranes utilized as the separator demonstrated good charge/discharge capacity and cycle performance.Use the electrospinning technique to deposite the PVDF onto the Celgard 2400 polypropylene microporous membrane. The argon atmospheric pressure plasma technique was used to treat the Celgard 2400 polypropylene microporous membrane, which can improve the adhesion between the electrospun PVDF fiber and the Celgard 2400 polypropylene microporous membrane. The electrolyte uptake of electrospun PVDF/Celgard 2400 polypropylene composite membrane was checked and it was found that the elecrospun PVDF fiber can greatly improved the affinity between the Celgard 2400 polypropylene microporous membrane and the electrolyte. Finally, the electrochemical stability window of the commercial Celgard 2400 polypropylene microporous membrane and the electrospun PVDF/Celgard 2400 polypropylene composite membrane was tested and the results showed that the electrospun PVDF/Celgard 2400 polypropylene composite membrane had relatively wider electrochemical stability window than the commercial Celagard 2400 polypropylene microporous membrane. |
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