Phase Interface Engineering of Metal Selenides Heterostructure for Enhanced Lithium-Ion Storage and Electrocatalysis

Abstract

Biphasic or multiphase heterostructures hold attractive prospects in engineering advanced electrode materials for energy-related applications owing to the appealing synergistic effect; however, they still suffer from unsatisfied electrochemical activity and reaction kinetics. Herein, guided by density functional theory calculation, a well-engineered selenides heterostructure with high-density biphasic interfaces of Ni3Se4-NiSe2 fastened in N, O-codoped carbon matrix was developed for high-performance lithium storage and electrocatalysis. By controlled selenylation of metal-organic framework (MOF), a series of NiSex@C hybrids (Ni3Se4@C, Ni3Se4/NiSe2@C-1, Ni3Se4/NiSe2@C-2, and NiSe2@C) with tunable biphasic components and grain sizes were prepared. Abundant two-phase interfaces with higher interface density are generated inside the Ni3Se4/NiSe2-1 induced by much smaller nanograins in comparison with the Ni3Se4/NiSe2-2, so that significant charge redistribution and faster electrons/Li+ ions transfer kinetics are achieved within the selenides, which are proved by the mutual verification of experiment performance and theoretical analysis. Benefitting from the optimized heterointerfaces, the Ni3Se4/NiSe2@C-1 manifests reduced electrode polarization, superior rate capability, and prolonged cyclic stability (621.3 mAh g-1 at 1 A g-1 for 1000 cycles; 362.3 mAh g-1 at 4 A g-1 for 2000 cycles) with respect to the Ni3Se4/NiSe2@C-2, as well as excellent performance in LiCoO2//Ni3Se4/NiSe2@C-1 full cell. Detailed electrochemical analysis confirmed rapid e-/Li+ diffusion rate，reaction mechanism and more pseudocapacitive energy for the Ni3Se4/NiSe2@C-1. Therefore, the Ni3Se4/NiSe2@C-1 showcases superior hydrogen evolution reaction (HER) and lithium storage performances. This work demonstrates the significance of interface modulation of multiphase heterostructures to boost the electrochemical performance in energy storage and conversion.

Keywords: metal selenides, heterostructure, phase interface, lithium-ion batteries, hydrogen evolution reaction