Preparation And Electrochemical Properties Of PEO-Al₂O₃ Hybrid Membranes And Biomass Derived Carbon Anode Materials

Today,lithium-ion battery is one of the most important energy storage devices.With the development of the society,the requirements are gradually increasing for capacity and energy density of lithium-ion battery.But the problems of safety of batteries and the storage of lithium resources have emerged.In order to solve the above problems,PEO hybrid membranes and biomass derived carbon anode materials of sodium ion battery are selected as research objects in this paper.Meanwhile,the work studied the structure of hybrid membranes and electrochemical performance of batteries.Meanwhile,the paper discussed the electrochemical performance and sodium storage properties of biomass derived carbon materials.The main contents and results are as follows:In this work,a series of poly?ethylene oxide??PEO?-aluminium oxide?Al₂O₃?hybrid membranes were prepared by a slurry coating method.The effects of the mass ratio of PEO/Al₂O₃ on PEO-Al₂O₃ hybrid membranes were systematically investigated.Scanning electron microscopy?SEM?,transmission electron microscope?TEM?,energy-dispersive spectrometer?EDS?,X-ray diffraction?XRD?,Fourier transform infrared spectra?FTIR?,X-ray photoelectron spectroscopy?XPS?,thermogravimetric analysis?TG?and combustion tests were performed to reveal the morphology,elements distribution,phase composition,surface chemical state and thermal stability of PEO-Al₂O₃ hybrid membranes.In addition,linear sweep voltammetry?LSV?,electrochemical impedance spectroscopy?EIS?,porosity and electrolyte uptake tests were employed to investigate the electrochemical stability,ionic conductivity,porosity and electrolyte uptake of PEO-Al₂O₃ hybrid membranes.The results showed that PEO-Al₂O₃-90 hybrid membrane has a high ionic conductivity?1.21×10^-33 S/cm?,high electrolyte uptake?260%?,good thermal stability,high porosity?47%?and wide electrochemical stabilization window?0⁴.8 V?.At the current density of 0.1 C,LiFePO₄|PEO-Al₂O₃-90|Li cells were assembled with PEO-Al₂O₃-90 hybrid membrane exhibited a high discharge specific capacity,superior cycling stability and enhanced safety.In this work,a series of carbon microspheres with uniform size and morphology were synthesized from yeast as biotemplates and carbon sources via a facile high-temperature pyrolysis method at 900 ^oC,1100 ^oC and 1300 ^oC,respectively.X-ray diffraction?XRD?,scanning electron microscopy?SEM?and Brunauer-Emmett-Teller?BET?tests were performed to reveal the phase composition,morphology and specific surface area of yeast derived carbon microspheres.The effect of pyrolysis temperature on the electrochemical performance of yeast derived carbon microspheres was systematically investigated.The results showed that the sample carbonized at 1100 ^oC exhibited the high reversible capacity of 205 mAh/g at 0.1 C?0.1 C=20 mA/g?and good cycling performance?reversible capacity of 186 mAh/g over 100 cycles?.The satisfactory electrochemical performance could be mainly attributed to large interlayer distance?0.361 nm?and low specific surface area?72 m²/g?,which is beneficial for the reversible insertion/extraction of sodium ions and improveing the initial coulomb efficiency of the batteries.This biotemplating strategy could not only realize the comprehensive utilization of biomass,but also provide a high potential anodic material for sodium-ion battery.