Capacity Contributing Conductive Cathode Additive for Sulfur Batteries

Thursday, 23 June 2016
Riverside Center (Hyatt Regency)
K. Sun (Brookhaven Nation Laboratory), D. Su (Brookhaven National Laboratory), C. A. Cama, R. DeMayo, J. Huang (Stony Brook University), Q. Zhang (Stony Brook Univesity), A. C. Marschilok, K. J. Takeuchi, E. S. Takeuchi (Stony Brook University), and H. Gan (Brookhaven National Lab)
The Lithium-Sulfur (Li-S) battery has been a subject of intensive research in recent years due to its potential to provide much higher energy density and lower cost than the current state-of-the-art lithium-ion battery technology.  However, both cell reaction active materials, sulfur and Li2S, are electronically non-conductive, which leads to the low electrode utilization and fast capacity fade during cell cycling.  Large amounts of non-active carbon host materials must be added to boost sulfur electrode electronic conductivity for high rate discharge, which lowers the sulfur electrode specific energy density.

Transition metal sulfides have been utilized as cathode material with high energy density and have been demonstrated to be rechargeable in lithium batteries.  Many of these sulfides are electronic conductive with conductivity comparable to that of graphite and carbon black.  Since they are also electrochemically active and can be cycled within the voltage window of sulfur battery, transition metal sulfides could be used as capacity contributing conductive cathode additive for sulfur batteries.

We have investigated Titanium Disulfide (TiS2), Pyrite (FeS2) and Cupric Sulfide (CuS) as capacity-contributing conductive cathode additives to the sulfur electrodes in Li-S battery.  Sulfur electrodes containing the metal sulfide additives showed improved power capability under high rate discharge.  While the cyclability of the hybrid electrodes vary widely depending on the type of conductive additive, different and unique electrochemical behaviors were observed for hybrid electrodes with TiS2, FeS2 and CuS respectively.  Improved coin cell cycling performance was observed with TiS2 as the cathode additive at 1C discharge rate.  The TiS2 distribution within the hybrid electrode showed significant impact on cell cycling capacity fade.  The mechanisms associated with the electrochemical performance of each chemical system are discussed.