Electrochemical Performance of Carbon/Sulfur as Lithium-Sulfur Battery Cathodes

MARIELA GISELA ORTIZ; SILVIA GRACIELA REAL; ARNALDO VISINTIN

Buenos Aires

Congreso; 20th Topical Meeting of the International Society of Electrochemistry,Advances in Lithium and Hydrogen Electrochemical Systems for Energy Conversion and Storage; 2017

Nowadays, rechargeablebatteries with higher energy density are required for our society due to the needs of cleaner and more efficientenergy systems and with the objective of supplying the increasing technologicaldemands. Commercial lithium batteries are systems based on intercalationcompounds able to delivering specific energies about 150-200 WhKg-1,one-third of their theoretical energy ( ≈ 600 Wh kg-1). It isdifficult for the reversible capacity of these intercalation compounds to beincreased, thus the need to explore new cathodes formed by lighter materialsand involving electrochemical reactions of more than one electron. An elementsatisfying these conditions is sulfur (with a theoretical capacity of 1675 mAhg-1and a specific energy of 2600 WhKg-1). Thelithium-sulfur battery has been investigated by different groups in past decades;however, there are serious drawbacks, which have not been overcome yet, so it limitsthe practical development of this system [3]. Moreover, sulfur is much moreabundant, inexpensive, and non-toxic compared to the transition-metal oxidecathodes.We present here thepreparation of composites with carbon and sulfur materials in a singlefabrication process: using S2C as the solvent. The characterizationof the prepared material was performed using optical techniques (X-raydiffraction, scanning electron microscopy and transmission) and itselectrochemical performance in lithium-sulfur batteries was studied usingelectrochemical techniques such as: charge-discharge cycles, galvanostaticdischarges to different currents and cyclic voltammetry. The prepared compositematerials delivered higher capacities in the first cycles (≈800 mAhg-1)and then it were stabilized at values around 60% of the initial capacity. Also,carbon electrochemical response was not observed, so its main function is toact effectively as an electron-conducting and support matrix.