Spontaneous built-in electric field in heterostructure electrocatalysts with high catalytic activity and conductivity: Inducing 3D nucleation of Li2S

Abstract

Lithium-sulfur (Li-S) batteries have become a research focus due to their high theoretical specific capacity and energy density. The shuttle effect and slow sulfur conversion kinetics of lithium polysulfides (LiPSs) severely hindered their practical application. Here, a N-doped carbon nanofiber self-supporting electrode modified with cobalt selenide/nickel selenide as a sulfur carrier (CoSe2/NiSe2@NCNFs) is designed and constructed. The experimental results show that a built-in electric field is formed at the interface of CoSe2/NiSe2 Mott-Schottky heterostructure, which promotes the conversion of LiPSs and induces 3D nucleation of Li2S. Furthermore, the calculation results of density functional theory clearly reveal high conductivity, adsorption and interfacial charge transfer between CoSe2/NiSe2 Mott-Schottky heterostructure electrocatalyst and LiPSs. As a result, the CoSe2/NiSe2@NCNFs/S cathode shows a specific capacity of 1050.8 mAh g−1 at 1 C, and maintains excellent cycling performance with a discharge capacity of 735.1 mAh g−1 and a capacity decay of 0.003 % per cycle over 1000 cycles. This work designed a Mott-Schottky heterostructure electrocatalyst to strengthen the adsorption and conversion of LiPSs and induce 3D nucleation of Li2S, providing a new idea for high-performance Li-S batteries.