Fair performance comparison of different carbon blacks in lithium–sulfur batteries with practical mass loadings – Simple design competes with complex cathode architecture

• Published in: Journal of power sources Vol. 296; pp. 454 - 461
• Main Authors: Jozwiuk, Anna, Sommer, Heino, Janek, Jürgen, Brezesinski, Torsten
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.11.2015
• Subjects: Carbon black; Lithium nitrate; Lithium-sulfur battery; Polysulfide adsorption; Redox shuttle; Redox shuttle; Carbon black; Lithium-sulfur battery; Polysulfide adsorption; Lithium nitrate
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.07.070

The lithium–sulfur system is one of the most promising next generation battery systems, as elemental sulfur is cheap, abundant and has a high theoretical specific capacity. Although much research is conducted on complex sulfur/carbon composites and architectures, it is difficult to compare the performance of the cathodes to one another. Factors, such as different electrolyte composition and cell components strongly affect the cyclability of the battery. Here, we show the importance of optimizing “standard” conditions to allow for fair performance comparison of different carbon blacks. Our optimal electrolyte-to-sulfur ratio is 11 μL mgsulfur−1 and high concentrations of LiNO3 (>0.6 M) are needed because nitrate is consumed continuously during cycling. Utilizing these standard conditions, we tested the cycling behavior of four types of cathodes with individual carbon blacks having different specific surface areas, namely Printex-A, Super C65, Printex XE-2 and Ketjenblack EC-600JD. Both the specific capacity and polysulfide adsorption capability clearly correlate with the surface area of the carbon being used. High specific capacities (>1000 mAh gsulfur−1 at C/5) are achieved with high surface area carbons. We also demonstrate that a simple cathode using Ketjenblack EC-600JD as the conductive matrix material can well compete with those having complex architectures or additives. [Display omitted] •Electrolyte-to-sulfur ratio greatly influences the cycling performance.•Nitrate is consumed continuously during cycling.•Large amounts of nitrate are needed for long-term cycling performance.•Carbon surface area correlates with polysulfide adsorption and specific capacity.•High surface area carbons perform well (>800 mAh gsulfur−1 at 1C over 600 cycles).