Published: September 01, 2011 r2011 American Chemical Society 16154 dx.doi.org/10.1021/ja2062659 | J. Am. Chem. Soc. 2011, 133, 16154–16160 ARTICLE pubs.acs.org/JACS Cathode Composites for LiÀS Batteries via the Use of Oxygenated Porous Architectures Rezan Demir-Cakan, †,‡ Mathieu Morcrette, †,‡ Farid Nouar, § Carine Davoisne, † Thomas Devic, § Danielle Gonbeau, ||,‡ Robert Dominko, ‡,^ Christian Serre, § G  erard F  erey, § and Jean-Marie Tarascon* ,†,‡ † LRCS, UMR CNRS 6007, Universit  e de Picardie Jules Verne, 33 Rue Saint-Leu, 80039 Amiens cedex, France ‡ ALISTORE-ERI, 80039, 33 Rue Saint-Leu, Amiens, France § Institut Lavoisier, UMR CNRS 8180, Universit  e de Versailles Saint-Quentin-en-Yvelines, 45 avenue des Etats-Unis, 78035 Versailles cedex, France ) IPREM-ECP, UMR CNRS 5254, Universit  e de Pau et des Pays de l'Adour, 2 avenue P. Angot, 64053 Pau, France ^ National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia b S Supporting Information ’ INTRODUCTION Developing batteries for load leveling and transport is still a formidable challenge, especially for materials chemistry, and will be a major focus of endeavor for years to come. The rechargeable lithium-ion (Li-ion) battery is regarded as the device of choice for the near future because of its higher energy density compared to other rechargeable batteries, enabling the development of smal- ler and lighter batteries that can store more energy. However, even Li-ion batteries will not be able to store sufficient energy for the extended driving range required by electric vehicles in the long term, therefore we need to explore new batteries that are different from Li-ion and offer a real step change in energy storage. Within this context, LiÀS batteries could be a viable option since they effectively possess higher theoretical specific energy over conventional Li-ion batteries, assuming complete reaction of Li and S to form Li 2 S (2600 Wh/kg or 2800 Wh/l) and present cost, environmental, and sustainable attributes. Although studies on the LiÀS system were initiated back to the early 60s, 1 the system has yet to conquer the marketplace, as a few scientific hurdles remain to be cleared. Among them are: (i) the use of a Li metal anode which brings safety problems, 2 (ii) the low active material utilization due to the insulating nature of both the sulfur itself and the polysulfide species resulting from its reduction, and (iii) the poor electrode cyclability, owing to the solubility in various electrolytes of the polysul fides generated during the battery operation. 3 Past research efforts have been devoted to address these issues. For instance, modifying electrolyte formulation via additives in order to form a protective surface film for Li electrode 4 or using polymers 5 rather than liquid-type electrolytes was attempted to restrain the polysulfides solubility. Besides, several approaches were pursued to prepare highly electronic conducting, porous C/S composites in order to capture polysulfide species within the elec- trode configuration. Among the most elegant ones is Nazar’s ap- proach 6 which relies on the use of ordered mesoporous carbon composite so as to provide both an electronic percolation path through the electrode and an adequate controlled porosity to Received: July 6, 2011 ABSTRACT: LiÀS rechargeable batteries are attractive for electric trans- portation because of their low cost, environmentally friendliness, and superior energy density. However, the LiÀS system has yet to conquer the marketplace, owing to its drawbacks, namely, soluble polysulfide forma- tion. To tackle this issue, we present here a strategy based on the use of a mesoporous chromium trimesate metalÀorganic framework (MOF) named MIL-100(Cr) as host material for sulfur impregnation. Electrodes containing sulfur impregnated within the pores of the MOF were found to show a marked increase in the capacity retention of LiÀS cathodes. Complementary transmission electron microscopy and X-ray photoelec- tron spectroscopy measurements demonstrated the reversible capture and release of the polysulfides by the pores of MOF during cycling and evidenced a weak binding between the polysulphides and the oxygenated framework. Such an approach was generalized to other mesoporous oxide structures, such as mesoporous silica, for instance SBA-15, having the same positive effect as the MOF on the capacity retention of LiÀS cells. Besides pore sizes, the surface activity of the mesoporous additives, as observed for the MOF, appears to also have a pronounced effect on enhancing the cycle performance. Increased knowledge about the interface between polysulfide species and oxide surfaces could lead to novel approaches in the design and fabrication of long cycle life S electrodes.