Te-doped Fe_(3)O_(4) flower enabling low overpotential cycling of Li-CO_(2) batteries at high current density

Li-CO_(2)batteries(LCBs)suffer from high overpotentials caused by sluggish CO_(2)reaction kinetics.This work designs a Te-doped Fe_(3)O_(4)(Te-Fe_(3)O_(4))flower-like microsphere catalyst to lower the overpotential and improve the reversibility of LCBs.Experimental results reveal that Te doping modifies the electronic structure of Fe_(3)O_(4)and reduces the overpotential.The stable Te-O bond between Te and C_(2)O^(2-)_(4)could effectively inhibit the dispro-portionation reaction of the latter,enabling the Te-Fe_(3)O_(4)cathodes to exhibit a remarkable capacity(9485 mAh g^(-1))and a long cycling life(155 cycles)with an overpotential of 1.21 V and an energy efficiency of about 80%at a high current density(2000 mA g^(-1)).Through the interaction between Te and Li_(2)C_(2)O_(4)to inhibit the dispro-portionation reaction,this work successfully achieves long-term cycling of LCBs with low overpotential at high current density.

Synergized oxygen vacancies with Mn_(2)O_(3)@CeO_(2)heterojunction as high current density catalysts for Li-O_(2)batteries

The application of Li-O_(2)batteries(LOBs)with ultra-high theoretical energy density is limited due to the slow redox kinetics and serious side reactions,especially in high-rate cycles.Herein,CeO_(2)is constructed on the surface of Mn_(2)O_(3)through an interface engineering strategy,and Mn_(2)O_(3)@CeO_(2)heterojunction with good activity and stability at high current density is prepared.The interfacial properties of catalyst and formation mechanism of Li_(2)O_(2)are deeply studied by density functional theory(DFT)and experiments,revealing the charge-discharge reaction mechanism of LOBs.The results show that the strong electron coupling between Mn_(2)O_(3)and CeO_(2)can promote the formation of oxygen vacancies.Heterojunction combined with oxygen vacancy can improve the affinity for O_(2)and LiO_(2)reaction intermediates,inducing the formation of thin-film Li_(2)O_(2)with low potential and easy decomposition,thus improving the cycle stability at high current density.Consequently,it achieved a high specific capacity of 12545 at 1000 mA g^(-1)and good cyclability of 120 cycles at 4000 mA g^(-1).This work thus sheds light on designing efficient and stable catalysts for LOBs under high current density.