Contactless Electric-field Driven Z Alignment Of Ceramic Ceramic Nanoparticles Within Polymer With Enhanced Ionic Conductivity

For the inorganic nanoparticles polymer films,the concentration and arrangemen t of nanoparticles have an important effect on the performance of film.The film with nanoparticles aligning along‘Z'direction has been proved better enhancement in ther mal,electric conductivity,and higher dielectric constant,in comparing with the isotro pic film.In this study,a contactless electric field are introduced to architect Z-direction ali gnment of the lithium aluminum germanium phosphate nanoparticles(LAGP,Li_1+xAl_x Ge_2-x?PO₄?₃)in the blend of polyethyeneoxide?PEO?and poly?ethylene glycol?diacryl ate?PEGDA?.The contactless electric field is implemented by applying a voltage to a n electrode pair composed of top electrode and a polymer/nanoparticle suspension-coa ted substrate electrode,separated in parallel by an air gap.This air-gap electrode facili tates alignment of ceramic nanoparticles in“Z”direction in solution and evaporating of the solvent.The kinetics of the alignment of LAGP in PEO during AC electric field application was investigated by measuring light transmission and temporal evolution of microscopic images with optical microscope.The aligned particles are frozen in the final film by evaporation of solvent and the curing of PEGDA.The morphology of the LAGP/PEO/PEGDA film with and without alignment wa s characterized with digital camera,scanning electron microscope?SEM?connected w ith an energy dispersive X-ray spectrometry?EDS?and Atomic force microscope?AF M?.In addition,X-ray Diffraction?XRD?,Dynamic thermomechanical analysis?DM A?,and Differential scanning calorimetry?DSC?were used to investigate the influenc e of the voltage on the crystalinity,glass transition temperature of the PEO.The effect of aligned structures on the ionic conductivity and electrochemical stability were inve stigated by using an electrochemical workstation.Results indicated that the nanoparticles can be aligned into the chains easily and chain rapidly frozen by evaporating of the solvent in an open space.under the contactl ess electric field.When loading of LAGP nanoparticles is 20 wt.%,The film with alig ned LAGP nanoparticles under 800 V of AC electric field exhibits an ionic conductivi ty 2.7 times,and the elongation at breaking 2.6 times of the film with random distribut ed LAGP inside at 25?,respectively.As a comparison,aligned LAGP/PEO/PEGDA nanocomposites were able to achieve comparable or better ionic conductive and mec hanical properties than those of unaligned nanocomposites at the same particle loadin g.On the other word,the flexibility of the polymer matrix were maintained while achi eving similar or higher ionic conductivity at much lower ceramic concentration.This approach can be applied to other ceramic systems,such as LLZO and sulfid es,to further enhance the ionic conductivity.Non-contact electric field also can be ap plied to fabricate the ultrathin polymeric composite film with the thickness of about m icrometers.