In-situ Electrochemical Catalysis In Lithium-air Battery

Li-O₂ battery has attracted worldwide attentions due to its super potential specific energy density（3600 Wh/kg）,and it has been considered as the next-generation energy storage device.However,Li-O₂ battery has a slow OER/ORR reaction kinetics which leading a great polarization and poor cycling performance,has not yet been commercialized.This is because the discharge product Li₂O₂ can not decompose immediately during the cycling of Li-O₂ battery and then accumulate in the positive electrode,blocking the holes,which eventually leads to the failure of the battery.The use of catalysts can break this bottleneck,accelerate OER/ORR kinetics and improve the cycle life of Li-O₂ battery.In this paper,we prepared novel catalysts by in-situ method to improve the electrochemical performance of Li-O₂ battery.Firstly,nano-Ru bifunctional catalyst were prepared by in-situ discharge reduction methode with the help of lithium battery,using Ru Cl₃ electrolyte.The Li-O₂ battery with nano-Ru catalyst can keep a stable cycling for 20 times with a low OER/ORR overpotential at the current density of 50 m A/g and 500 m Ah/g cut-off capacity.In addition,this method is very simple,safe and reliable.Secondly,we assembled lithium-ion battery with carbon paper（CP）cathode,1 M Li Cl O₄/DMSO electrolyte and lithium metal anode.Then we obtained the activated CP（ACCP）by in-situ discharge method.Li-O₂ battery with ACCP cathode has a very low OER/ORR overpotential.During the first seven cycles,the OER potential remained below 3.5 V and the ORR potential was about 2.75 V.In addition,we applied ACCP to Li-S battery,and the Li-S battery can stable cycling for 30 cycles and still has a high capacity at the current density of 0.3 m A/cm².Finally,we studied the electrochemical performance of DMEA as a bifunctional additive in Li Co O₂ battery.After adding 0.5 wt%DMEA into Li PF₆ electrolyte,Li Co O₂battery showed better cycle stability and capacity retention.After that,we applied DMEA to lithium-air battery.It was found that the first OER overpotential of Li-O₂ battery was only 0.31 V after adding 20 wt%DMEA to 1 M Li TFSI/TEGDME electrolyte,and the discharge capacity was greatly improved too.