Revealing the electrochemical mechanism of the conversion-type Co3S4 in a novel high-capacity Mg-Li hybrid battery

Abstract

A dendrite-less Mg anode is coupled with an insertion-type cathode to construct a Mg-Li hybrid ion battery competitive to the state of art Li-ion batteries. However, the issue of limited energy density restricts the practical application of Mg-Li hybrid battery. Herein, it is the first time to assemble an ultrahigh-capacity Mg-Li hybrid battery with spinel Co3S4 cathode and Mg anode. The particle-like Co3S4-F delivers the initial high discharge capacity of 779.8 mAh g−1 and retains 399.5 mAh g−1 in the 100th cycle with discharge voltage platform at 1.10 V vs. Mg2+/Mg and high energy density of 439.5 Wh kg−1 at 0.1 A g−1, much higher than that of reported chalcogenides in a nucleophilic APC-based Mg-Li hybrid electrolyte. The synergistic effect of hierarchical Co3S4-F micro/nano particles and APC-LiCl hybrid electrolyte promotes outstanding electrochemical performance of spinel Co3S4-F upon cycling. The conversion reaction of the Co3S4-F to metallic Co and sulfide Li2S contributes to ultrahigh capacity of Mg-Li hybrid battery during the discharge process. This work will pave the way for the development of the spinel chalcogenides as cathode materials for high-energy-density Mg-Li hybrid batteries.