Preparation And Performance Of Pd-modified Porous Carbon Integrated Cathod In Non-aqueous Lithium-air Battery

In this paper, the integrated cathode material Pd-modified hollow sphere carbon forlithium-air battery is synthesized via hard template and electrophoretic deposition, whichis characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TG-DSC),scanning electron microscope(SEM), energy dispersive spectrometer(EDS), transmissionelectron microscopy (TEM), Brunauer-Emmer-Teller(BET) surface area measurement,Raman spectroscopy, infrared spectroscopy (IR). A various electrochemical methodsincluding the galvanostatic charge and discharge, electrochemical impedance spectroscopy(EIS) and cycle voltammetry(CV) are employed for the study on electrochemicalperformance. We carry out a systematic study on the morphology, structure andelectrochemical properties of the composites, in addition, the quantitative analysis of theproducts produced in the discharge process is carried out after different cycles.The XRD pattern presents that Pd particles are highly crystalline and loaded in thehollow carbon sphere successfully. TG-DSC test shows the content of Pd is25wt.%. Thespherical carbon is firmly deposited in the scheme of the carbon paper, which can beobserved by SEM. The material consists of two kinds of pore structure obtained from thepore distribution curve, respectively20-100nm and3nm. The specific surface area of thesample is127m2/g with BET method, the pore volume is determined to be0.22cm3/gusing BJH method. The TEM results demonstrate the particle size of Pd is10-15nm andthe wall thickness of the carbon sphere is9.19nm.The overpotential of Li-O2cells with PHSC cathode is less300mV and490mV thanthose with SP and HSC cathode at a current density of300mA/g and a fixed capacity of3000mAh/g, significantly improving the efficiency of the energy conversion. CV testsfurther confirm the result. Moreover, the Li-O2battery with PHSC cathode presentshigh-rate with a capacity of5900mAh/g at a current density of1.5A/g, and long cyclingstability of205cycles at a current density of300mA/g and a specific capacity limit of1000mAh/g. We characterized the discharge product by SEM, detecting Li2O2is disc-shaped in SPelectrode while the Li2O2in PHSC appears a sheet structure with thickness of about10nm,uniformly growing on the surface of carbon sphere. Also, the quantitative analyse of theproducts produced in the discharge process is carried out after different cycles,discovering that the content of Li2O2is up to81.6%in PHSC electrodes after one hundredcycles.The performance of lithium-air battery with the Pd-modified porous carbonintegrated cathode has been greatly improved. These superior properties could beexplained by unique porous structure with effectively catalytic Pd nanoparticles. It will bea desirable approach to design more advanced cathode architecture for lithium-air battery.