Carbonaceous separators modified to improve the cyclability of lithium sulfur batteries

CECILIA CALDERON; GERMAN LENER; KARIM SAPAG; ARNALDO VISINTIN; EZEQUIEL LEIVA; DANIEL BARRACO

Congreso; 20th Topical Meeting of the International Society of Electrochemistry; 2017

Lithium?sulfur batteries are especially promising electrochemical systems because the active material is sulfur, which is economical, abundant, and non toxic and has a hightheoretical capacity of 1672 mAh/g and energy density of 2600 Wh/kg. The high energy density is due to the phase transitions undergone by sulfur which allows capturing morelithium ions than the transition metal based materials currently used. Nevertheless this material has several problems that need solution. Some of these problems are: Li 2 S and S 8are insulating, so it is necessary to cover them with some conductive material; the material has a change of volume of 80% between lithiated and delithiated phase; polysulfidesformed as intermediates are very soluble in the electrolyte, causing a loss of active material; shuttle effects takes place, where the efficiency of the lithium anode can be lowereddue the passivation with insoluble sulfides; metallic lithium is used as anode, generating degradation of the electrolyte; degradation of electrolyte by the polysulfides.In this work we used modified separators with mesoporous carbon (CMK3 prepared in the laboratory and pretreated with HNO 3 or NH 3 ) polyacrylic acid (PAA) and oxydizedcarbon nanotubes (CNTox). As active material we used the same mesoporous carbon as host and sulfur particles were deposited by melting in argon atmosphere.