Trapping Lithium Selenides with Evolving Heterogeneous Interfaces for High-Power Lithium-Ion Capacitors.

ABSTRACT

Transition metal selenides anodes with fast reaction kinetics and high theoretical specific capacity are expected to solve mismatched kinetics between cathode and anode in Li-ion capacitors. However, transition metal selenides face great challenges in the dissolution and shuttle problem of lithium selenides, which is the same as Li-Se batteries. Herein, inspired by the density functional theory calculations, heterogeneous can enhance the adsorption of Li2 Se relative to single component selenide electrodes, thus inhibiting the dissolution and shuttle effect of Li2 Se. A heterostructure material (denoted as CoSe2 /SnSe) with the ability to evolve continuously (CoSe2 /SnSe→Co/Sn→Co/Li13 Sn5 ) is successfully designed by employing CoSnO3 -MOF as a precursor. Impressively, CoSe2 /SnSe heterostructure material delivers the ultrahigh reversible specific capacity of 510 mAh g-1 after 1000 cycles at the high current density of 4 A g-1 . In situ XRD reveals the continuous evolution of the interface based on the transformation and alloying reactions during the charging and discharging process. Visualizations of in situ disassembly experiments demonstrate that the continuously evolving interface inhibits the shuttle of Li2 Se. This research proposes an innovative approach to inhibit the dissolution and shuttling of discharge intermediates (Li2 Se) of metal selenides, which is expected to be applied to metal sulfides or Li-Se and Li-S energy storage systems.