Interface engineering in NiSe2/Ni2Co/CoSe2 heterostructures encapsulated in hollow carbon shells for high-rate Li-Se batteries.

The sluggish conversion reaction and the accompanying huge volume fluctuation greatly hinder the application of lithium-selenium (Li-Se) batteries. Therefore, reasonably constructing stable carbonaceous hosts with efficient electrochemically active sites is particularly essential for promoting the development of Se cathodes. Herein, a metal-organic solid derived carbon host with multiple heterogeneous NiSe2/Ni2Co/CoSe2 interfaces was fabricated via in situ selenization. The formation of multiple heterointerfaces introduced subtle atomic array distortions, which provided additional electrochemically active sites compared with single heterointerfaces. Besides, the establishment of a built-in electric field was favorable for electron transfer and the absorption of Li+, thereby accelerating the reaction kinetics. Depending on the hollow structure and the heterogeneous catalysts, Li-Se batteries with NiSe2/Ni2Co/CoSe2@Se cathodes delivered reversible capacities of 503 and 324 mA h g-1 after 900 and 2200 cycles at 1 and 12 C, respectively. This work revealed the synergistic mechanism of multiple heterostructures composed of a Ni2Co alloy and in situ derived bimetallic selenides for Se cathodes and provided new insights into the exploitation of energy storage materials.