Hollow (Co 0.62 Fe 1.38 )FeO 4 /NiCo 2 O 4 nanoboxes with porous shell synthesized via chemical precipitation: A novel form as a high performance lithium ion battery anode Manab Kundu a, *, 1 , Gopalu Karunakaran b, c, **, 1 , Evgeny Kolesnikov b , Arkhipov Dmitry b , Mikhail V. Gorshenkov d , Denis Kuznetsov b a Department of Material Science and Engineering, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway b Department of Functional Nanosystems and High-Temperature Materials, National University of Science and Technology MISiS, Leninskiy Pr. 4, Moscow, 119049, Russia c Department of Biotechnology, K. S. Rangasamy College of Arts and Science (Autonomous), Tiruchengode, 637215, Tamil Nadu, India d Department of Physical Materials Science, National University of Science and Technology MISiS, Leninskiy Pr. 4, Moscow,119049, Russia article info Article history: Received 22 January 2017 Received in revised form 22 March 2017 Accepted 24 March 2017 Available online 27 March 2017 Keywords: Mixed metal oxides Hollow nanoboxes Energy storage and conversion Lithium-ion batteries Electrochemical performance abstract Transition metal oxides containing different metal cations, also called as mixed metal oxides (MMOs), have conrmed improved electrochemical activities in comparison with single metal oxides (SMOs, containing single metal cations). In this study, for the rst time, we have synthesized the hollow (Co 0.62 Fe 1.38 )FeO 4 /NiCo 2 O 4 nanoboxes by simple and cost effective chemical precipitation method and investigated its lithium storage property. The uniqueness of this composite material is the hollow nano- structure with a very thin porous shell, which has rarely reported previously. The observed surface area of nanoboxes is 21.8 m 2 g 1 with average pore size of 4 nm. As a results, the (Co 0.62 Fe 1.38 )FeO 4 /NiCo 2 O 4 nanoboxes manifests a high reversible capacity of around 835.5 and 676.2 mAh g 1 over 350 cycles at a current densities of 200 and 500 mA g 1 , respectively. The nano-dimention with hollow structure not only beneted electron and Li-ion transportation, it also provided large electrodeeelectrolyte contact area. Furthermore, the high reversible capacity in (Co 0.62 Fe 1.38 )FeO 4 /NiCo 2 O 4 nanoboxes electrodes is most likely attributed to the synergistic electrochemical activity of both the phases, (Co 0.62 Fe 1.38 )FeO 4 and NiCo 2 O 4 . Hence, based on high reversible capacity as well as an outstanding rate performance, the (Co 0.62 Fe 1.38 )FeO 4 /NiCo 2 O 4 nanoboxes electrode sheds light on commercial applications as an alternative lithium-ion battery anode material. © 2017 Elsevier Inc. All rights reserved. 1. Introduction With the ever increasing demand for high performance and long cycle life lithium-ion batteries (LIBs), a large variety of materials including transition/non-transition metal oxides are investigated intensively [1e5]. Among the various anode materials, transition metal oxides (TMOs) have attracted signicant attention because of their remarkably high theoretical capacities (>700 mAh g 1 ) [6]. However, the intrinsic poor electrical conductivity and huge volume variations during the cycling process (lead to dramatic capacity fading, poor cycling stability and poor rate capability) hampered the practical application of TMOs. Based on some recent research nd- ings, hybrid TMO hetero structures resulted by the incorporation of conductive phases such as metals [7] or cushioning carbonaceous materials [8,9], exhibited improved electrochemical performances. However, as these additives deliver limited capacity, hence need to compromise the total achievable capacity. In order to address this limitation, new types of hybrid TMO hetero structures such as Co 3 O 4 /Fe 2 O 3 [10], Fe 2 O 3 /MnO 2 [11] and so on, are scrupulously tailored. The improved electrochemical performance in these hier- archical nanohybrids, can be explained by the synergistic inherent from each component. In recent years, MMOs, with different metal * Corresponding author. ** Corresponding author. Department of Functional Nanosystems and High- Temperature Materials, National University of Science and Technology MISiS, Leninskiy Pr. 4, Moscow,119049, Russia. E-mail addresses: manab.kundu@ntnu.no, chemmanab@gmail.com (M. Kundu), karunakarang5@misis.ru, karunakarang5@gmail.com (G. Karunakaran). 1 Both the author's contributed equally to this work. Contents lists available at ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso http://dx.doi.org/10.1016/j.micromeso.2017.03.045 1387-1811/© 2017 Elsevier Inc. All rights reserved. Microporous and Mesoporous Materials 247 (2017) 9e15