Realizing ultra long-cycle stability and reversibility for Li-O2 batteries with electron mobility modulated NiAl LDH@Cu2S heterostructure

Abstract

Developing an efficient and highly catalytic cathode is crucial to the advancement of rechargeable Li-O₂ batteries for utilizing their high theoretical energy density. However, due to the sluggish kinetics of the oxygen-involved reactions, the problems of short lifespan and large overpotential prevent their widely practical applications. Thus, cathodes are designed to enhance the adsorption capacity for oxygen and modulate the electron mobility for Li-O₂ batteries. Herein, NiAl layered double hydroxide (LDH)@Cu₂S heterostructure with extremely large specific surface area and numerous exposed active sites is designed, combining snowflake-shaped Cu₂S and dispersed two-dimensional layered NiAl LDH. Excitingly, NiAl LDH@Cu₂S cathode exhibited a large specific discharge capacity of 14,519 mAh g^-1 at a current density of 100 mA g^-1 and prolonged cycle life up to 275 cycles at 300 mA g^-1 with a cut-off capacity of 600 mAh g^-1, accompanied by a low discharge overpotential of 0.14 V at the first cycle. Theoretical calculations demonstrated that the excellent electrochemical performance stems from the optimized adsorption energy of the NiAl LDH@Cu₂S structure for reactants and intermediate products, which reduces the energy barrier of discharge/recharge process. Therefore, benefited from the modulation of electron mobility and the promoted adsorption of oxygen, NiAl LDH@Cu₂S heterojunction can display remarkable cycle stability and reversibility as the cathode catalyst, suggesting great application prospects for enhanced Li-O₂ batteries.