In pursuit of catalytic cathodes for lithium–oxygen batteries Ali Eftekhari * ab and Balaji Ramanujam c Li–O 2 batteries are among the most promising electrochemical energy storage systems, which have attracted significant attention over the past five years due to their potential to satisfy new demands such as powering electric vehicles. However, Li–O 2 batteries are lagging behind their rivals, because of the complicated nature of the cathode processes. Despite numerous efforts, our knowledge is very limited to design the practical cathodes. This review aims to survey the studies reported in the literature to provide a comprehensive perspective on the topic. The base material for the cathodes is typically high surface area carbon, but its architecture should be engineered to maximize the reaction efficiency. Although there are controversies about the role of catalysts in the cathode process, utilizing an appropriate catalyst seems to be mandatory. Precious metals can significantly reduce the overall overpotential but make no contribution to the specific capacity and cyclability, which is still one of the key issues of Li–O 2 batteries. Other transition metals and their oxides have shown promising results, yet far from being practical, as they reduce the specific capacity of the base carbon cathode. In any case, the structural design of the materials (both carbon and catalysts) at the atomic scale is of utmost importance to increase the number of active sites on which the charge transfer is fast enough to conduct the cathodic reactions. Another interesting point, which has not been recognized yet, is that most of the promising materials display active pseudocapacitive behavior in their original electrochemical studies. Although pseudocapacitance is not directly connected with the catalytic Ali Eekhari is a professor of chemistry temporarily with the University of Ulster and Queen's University Belfast. He has worked in different capacities in various universities across 4 continents and founded two internationally recognized academic schools from scratch, which were considered as exceptional success stories by major media such as the British newspaper, The Guardian. His research interest is focused on the material design for electro- chemical systems and he has worked on energy storage systems for 20 years. He is the principal author of over 100 papers published in leading scholarly journals and has supervised over 110 post- doctoral researchers and graduate students. He is the President of the American Nano Society. Balaji Ramanujam is a research officer in Madanapalle Institute of Technology and Science, Andhra Pradesh, India. He received his Integrated Master of Science in Chemistry from Pon- dicherry University and Doctoral Degree in Chemistry from Indian Institute of Technology Bombay. He extended his research work at California State University, Boise State University, and Jimma University as a Post- doctoral Fellow. His research work focuses on computational design of various applied materials and improvement of their properties for applications that are not limited to energy storage & production, spintronics, optoelectronics, structural cladding, sequestering and sensing. Apart from computational materials, he also has a wide range of interest in various computational chem- istry and biology problems. Cite this: J. Mater. Chem. A, 2017, 5, 7710 Received 5th February 2017 Accepted 25th March 2017 DOI: 10.1039/c7ta01124e rsc.li/materials-a a The Engineering Research Institute, Ulster University, Newtownabbey BT37 OQB, UK. E-mail: eekhari@elchem.org b School of Chemistry and Chemical Engineering, Queen's University Belfast, Stranmillis Road, Belfast BT9 5AG, UK c Department of Chemistry, Madanapalle Institute of Technology and Science, Madanapalle, Andhra Pradesh 517325, India 7710 | J. Mater. Chem. A, 2017, 5, 7710–7731 This journal is © The Royal Society of Chemistry 2017 Journal of Materials Chemistry A REVIEW