Fishing-net-shaped cobalt oxide microspheres for effective polysulfide reservoirs of rechargeable Li-S battery cathodes

Abstract

Hole-embedded one-directional two-dimensional sheet-assembly cobalt oxide microspheres are synthesized and assessed as effective encapsulation media for polysulfides in cathodes of lithium-sulfur batteries. The cathode of fishing-net-shaped cobalt oxide compounds incorporated with sulfur provides exceptional electrochemical properties such as a high Coulombic efficiency (99%), stable capacity fading, and a reversible capacity of 925 mA h g(-1) at 1 C, which is 22% higher than that of the conventional nanoparticulate cobalt oxide/sulfur electrode. The enhanced electrochemical behavior is attributed to the effective polysulfide adsorbent and hierarchically designed porous cobalt oxide with a coaggregated framework. The controlled pore-embedded particle size is an essential parameter determining the capture of the mobile polysulfides, rather than the use of numerous mere highly porous encapsulants, such as nanoparticulate cobalt oxides.