The Research Of Platinum Based Catalysts In Organic Lithium Air Battery

Lithium-air batteries have ultra-high energy density. The ideal reversibledischarge product is Li2O2in the organic lithium-air batteries. But it is preferred togenerate irreversible and insulated products like Li2CO3and alkyl lithium carbonateduring the cycles due to the decomposition of electrolytes. So we focus on the studyof Pt-based bifunctional oxygen catalysts in organic systems.First，The EC/DEC/EMC and DMSO organic electrolytes is tested by Pt/Ccatalyst which is synthesized by a microwave-assisted polyol process. No chargecapacity is obtained in the EC/DEC/EMC system. In contrast, discharge capacityand charge capacity of9298mAh·gC1and1425.5mAh·gC1are observed in DMSOsystem, and the initial voltage efficiency reaches78.1%.PtM/C(M=Pd, Ru, Au) catalysts are synthesized and optimized. Among threekinds of carbon support, XC-72, Super P and Ketjin Black, KB shows the best cycleperformance up to50cycles with a curtaining capacity of1,000mAh·gC1. Thedischarge platform is stable at around2.75V. Choose KB as the support and studythe influence of PtPd、PtRu and PtAu on the performances of catalysts. Au is foundto be good for charging process in lithuim-air batteries. Different ratios of Pt andAu are studied, the results indicate that higher content of Au benefits OER process.Furthermore, h-PtAu/XC-72with a―flower clusters‖structure of PtAu in thecatalyst is developed. The capacity only declines by10%until49th cycle with acurtaining capacity of1,000mAh·gC1, which is more than45times than ordinaryPtAu/XC-72catalyst. Kenitic analysis suggestes that the electron number of oxygenreduction reaction on PtAu/KB is estimated to be1in DMSO system, O2istransformed toO2firstly.IrO2is helpful to reduce the charge potential of lithium air batteries and toimprove the voltage efficiency. The bifunctional effect of Pt/IrO2is studied, inwhich IrO2plays as the support. The performance of L6-IrO2in which La2O3content is60%is the best among the IrO2synthesized with different proportion ofLa2O3templates. The initial charge platform for L6-IrO2is3.58V, and the voltageefficiency can reach78.5%. L6-IrO2can cycle24times with no significant decaywith limiting capacity to500mAh/g. Pt/L-IrO2with Pt content of60%shows the best performance. Pt/P-IrO2with IrO2prepared by P123as temple demonstratesgood cycle stability up to30cycles with a curtaining capacity of500mAh/g.Voltage efficiency is70%for the1st cycle and remains above80%until the29thcycle. Pt/IrO2-KB with IrO2and KB as mixed support shows the poor performance,as a result of the deterioration effects of carbon on the cycle performance oflithium-air batteries.