Vol.:(0123456789) 1 3 J Appl Electrochem (2017) 47:497–506 DOI 10.1007/s10800-016-1035-0 RESEARCH ARTICLE Cobalt-doped mesoporous carbon nanofbres as free-standing cathodes for lithium–oxygen batteries Sandra Martinez Crespiera 1  · David Amantia 1  · Etienne Knipping 1  · Christophe Aucher 1  · Laurent Aubouy 1  · Julia Amici 2  · Juqin Zeng 2  · Usman Zubair 2  · Carlotta Francia 2  · Silvia Bodoardo 2   Received: 7 October 2016 / Accepted: 27 December 2016 / Published online: 18 February 2017 © Springer Science+Business Media Dordrecht 2017 of Co nanoparticles enhances the degree of graphitiza- tion of the CNFs, which is benefcial to CNF conductivity. Measured BET surface areas of Co-doped CNFs are in the range of 40–300 m 2 g − 1 , depending on Co content. Results show that the Li–O 2 cell comprising the Co-doped CNF free-standing cathodes can deliver specifc capacities of 3700 mA h g − 1 based on the total mass of the electrodes and good cycling performance is achieved at the curtailed capacity of 100 mA h g − 1 . The good performance of the Co-doped CNFs may be attributed to the mesoporous struc- ture of CNFs which could facilitate the deposition of solid products during discharge and decrease the mass transport resistance. Diferent morphologies of the Li 2 O 2 crystals obtained during discharge with Co-doped CNF cathodes support the hypothesis that the presence of Co may induce alterations by forming easily decomposable Li 2 O 2 . Abstract Herein, we present binder-free O 2 electrodes of mesoporous carbon nanofbres and Co nanoparticles (Co- doped CNF). Such electrodes are synthesized using elec- trospinning techniques coupled with subsequent thermal treatments. The fbre-based mats behave as free-standing electrodes due to the presence of 3D cross-linked web struc- tures, and thus additional metal mesh or gas difusion layer supports are not required. The absence of polymeric bind- ers in the cathode avoids side reactions due to binder insta- bility during cell cycling. The Co-doped CNFs are char- acterized by feld emission scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, X-ray difraction and Raman analysis. CNFs are decorated by homogeneously distributed Co (0) nanoparticles, with sizes in the range of 10–50 nm and Co content lower than 10 wt%. N 2 adsorption–desorption measurements show that the specifc surface area of the CNFs is greatly afected by incorporation of the metal nanoparticles. The introduction * Silvia Bodoardo silvia.bodoardo@polito.it 1 Leitat Technological Center, Carrer de la Innovació, 2, 08225 Terrassa, Barcelona, Spain 2 Department of Applied Science and Technology (DISAT), Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy