The synthesis of a hybrid graphene–nickel/manganese mixed oxide and its performance in lithium-ion batteries Marcos Latorre-Sanchez a , Pedro Atienzar a , Gonzalo Abella ´n b , Marta Puche a , Vicente Forne ´s a , Antonio Ribera b , Hermenegildo Garcı´a a, * a Instituto de Tecnologı ´a Quı ´mica CSIC-UPV, Universidad Polite ´cnica de Valencia, Avenida de los Naranjos s/n, 46022 Valencia, Spain b Instituto de Ciencia Molecular, Universidad de Valencia, Catedra ´ tico Jose ´ Beltra ´n 2, 46980 Paterna, Valencia, Spain ARTICLE INFO Article history: Received 17 June 2011 Accepted 3 September 2011 Available online 8 September 2011 ABSTRACT Mixing of aqueous suspensions of delaminated NiMn layered double hydroxide (LDH) and graphene oxide leads to the instantaneous precipitation of a hybrid material that after cal- cination under inert atmosphere at 450 °C leads to Ni 6 MnO 8 nanoparticles deposited on lar- ger reconstituted graphene sheets. This material exhibits electrical conductivity similar to graphite, superparamagnetism and can be used as an anode for Li-ion batteries. A maxi- mum capacity value of 1030 mA h g 1 was found during the first discharge, and capacity values higher than 400 mA h g 1 were still achieved after 10 cycles. The methodology used here should allow the preparation of a large variety of hybrid graphene-metal oxide mate- rials starting from other LDHs in which the properties derived from both constituents coexist. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Hybrid inorganic/organic materials have found many applica- tions because they allow combining the properties of inor- ganic solids such as robustness, durability and mechanical strength with those introduced by the organic component such as functionality, tunability and convenient derivatiza- tion by synthesis [1]. Recently, graphene and related materials have attracted a considerable attention due to their high con- ductivity, high Young’s modulus and the possibility to be tai- lored by chemical modification [2–4]. There are many hybrid materials constituted by a combi- nation of active carbon and inorganic oxides [5]. Among the possible applications of these hybrid solids containing car- bon, those related to energy storage such as their use in sup- ercapacitors and Li-ion batteries are of large importance [6–9]. Also this type of hybrids has a large potential in other areas such as catalysis and engineering composites. Considering the special 2D morphology of graphene oxide (GO) sheets and that they typically bear negative charges, it oc- curred to us that colloidal suspensions of these carbonaceous materials can be suited for preparation of hybrids with layered metal oxides and layered double hydroxides (LDHs) bearing positive charges. In this way the possibility of obtaining a hy- brid material having in intimate contact negative GO sheets and positive LDH lamellae could be realized. Herein we report a simple preparation procedure based on precipitation and calcination of GO and NiMn–LDH nano- sheets to produce a hybrid graphene/Ni 6 MnO 8 material. The conducting and magnetic properties of the resulting material derive from the presence of graphene and the inorganic com- ponent, respectively. The interest and potential of this hybrid material based on graphene have been exemplified by using it as anode for Li-ion batteries. Tirado and co-workers were the first authors who studied the electrochemical behavior of Ni 6 MnO 8 and related mixed 0008-6223/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbon.2011.09.007 * Corresponding author: Fax: +34 96387 7809. E-mail address: hgarcia@qim.upv.es (H. Garcı ´a). CARBON 50 (2012) 518 – 525 Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/carbon