Preparation And Performance Of Biomass Derived Carbon Electrode Materials And Their Catalysts For Li-air Batteries

Li-Air batteries have attracted much attention due to its low cost and high theoretical specific capacity（11425 Wh/kg）.Without using noble metal-based catalysts,it is urgent to develop cheap and efficient cathode materials for commercial application of Li-Air batteries.On the one hand,biomass materials have low cost,simple preparation method,large specific surface area and porous structure,which can be used as cathode materials for Li-Air batteries to enhance the conductivity of the battery and accelerate the speed of ion transfer.On the other hand,the performance of Li-Air batteries can be further improved by loading efficient transition metal compound catalysts on cathode materials.In this paper,grapefruit peel was used as raw material to prepare biomass derived carbon,which was loaded with transition metal compound catalyst and directly used as cathode material for Li-Air electrode.The main research contents and conclusions of this paper are as follows:（1）Three dimensional self-supporting materials were prepared NiFeP@NC/BC（NC:N-doped C,BC:biomass carbon）electrode for Li-Air batteries.Firstly,Prussian blue analogue（PBA）was deposited on grapefruit peel,then red phosphorus was used as phosphorus source for phosphating.The as-prepared electrode was directly used as cathode of Li-Air batteries.The NiFeP@NC/BC cathode has high electron transport capacity and sufficient accessible reaction sites provided by transition metal phosphide（TMP）catalysts.The experimental results show that the battery has good electrochemical performance,the specific capacity is up to 10.9 mAh·cm^-2 and the cycle life is more than 90 cycles at the current density of 0.05 mA·cm^-2.（2）N-doped carbon containing NiFe and NiCx（NiCx-NiFe-NC）were prepared by bimetallic Prussian blue analogues supported on biochar,which were used as a novel self-standing cathode for Li-Air batteries.The specific discharge capacity of the Li-Air battery was 27.14 mAh·cm^-2 at a stable discharge voltage of 2.75 V.The excellent electrocatalytic performance of the catalysts in the reaction of Li-Air batteries is attributed to:（1）The d-orbital of Ni are hybridized with s and p-orbitals of carbon in NiC_x-NiFe-NC,formed at 900°C.（2）There is a synergistic effect among the components of NiC_x-NiFe-NC.（3）The structure of NiC_x-NiFe-NC efficiently improved the electron and ion transfer between the cathode and the electrolyte during the electrochemical processes.This paper has 20 figures,5 tables,and 98 references.