Optical Materials 102 (2020) 109831 Available online 19 March 2020 0925-3467/© 2020 Published by Elsevier B.V. Simulated synthesis and structure of Li x TiO 2 nanosheets as anode material for lithium ion batteries B.N. Rikhotso a, * , M.G. Matshaba a , D.C. Sayle b , P.E. Ngoepe a a University of Limpopo, Materials Modelling Centre, Private Bag X 1106, Sovenga, 0727, South Africa b University of Kent, School of Physical Sciences, Canterbury, Kent, CT2 7NZ, United Kingdom A R T I C L E INFO Keywords: Atomistic simulation Recrystallisation Li x TiO 2 nanosheet Li ion batteries ABSTRACT Nano-architectured Li x TiO 2 are promising as anode electrode materials for lithium rechargeable batteries due to their ability to accommodate and transport lithium atoms at low and elevated temperatures. In the current study, lithiated nanosheets with concentrations, Li 0 . 03 TiO 2 and Li 0 . 07 TiO 2 , were crystallised from amorphous precursors at 2000K, using large scale molecular dynamics (MD) simulation method, which was followed by a cooling process towards 0 K. The cooled nanosheets, Li 0 . 03 TiO 2 and Li 0 . 07 TiO 2 , were subsequently heated at temperature intervals of 100 K from 100 K to 500 K with a Nose-Hoover thermostat. The calculated Ti-O radial distribution functions (RDFs), were used to confrm the extent of crystallisation after cooling. The simulated X-ray diffraction (XRD) spectra, at low (0 K) and high (500 K) temperatures, exhibit peaks associated with both rutile and brookite polymorphs. Microstructural features also depicted diffusion pathways with rutile and brookite character, consistent with XRD results. These results confrm that the Li 0 . 03 TiO 2 and Li 0 . 07 TiO 2 nanosheets are good can- didates for anode materials in lithium ion batteries (LIB), since they can contain and transport lithium ions well, even under higher temperature conditions. 1. Introduction Prolonged cycle viability, inexpensive and excessive environmental compatibility are some of the most properties of titanium dioxide (TiO 2 ), which are classifed as most favorable anode attributes for lithium-ion batteries (LIBs) [1]. Fundamentally, TiO 2 (depending on polymorph) has adequate high lithium insertion/extraction potential (1.6–1.8 V vs. Li/Li þ ), which can articulately restrain the formation of a solid elec- trolyte interface (SEI) layer as well as lithium plating on the electrode, further appending signifcance to the safety of the overall battery [2]. Nonetheless, TiO 2 is faced with drawback charge capacity due to its low lithium diffusivity (from 1 � 10 15 to 1 � 10 9 cm 2 s 1 ) and electronic conductivity (from 1 � 10 12 to 1 � 10 7 S cm 1 ) [3]. Furthermore, the theoretical capacity (170 mA h g 1 ) of TiO 2 is only half that (372 mA h g 1 ) of the present anode material, i.e., graphitic carbon. These diff- culties, unfortunately, result in a predicament for TiO 2 when it is assessed as an anode material in LIBs. In order to improve the charge capabilities of TiO 2 , a feasible solution involves generating various nanostructures, including 1D nanotubes [4] and nanofbers [5] 2D nanosheet [6] or even complicated 3D nanostructures (e.g., nanoporous, nanospheres and bulk nanostructures) [7] with their highly energetic constituent elaborately exposed, thereby offering shorter lithium diffu- sion pathways and creating substantial contact areas between the elec- trode and electrolyte. Further constructive approach is to introduce high temperature variance into the generated nanosheets architectured structures using molecular dynamics simulations under amorphisation and recrystallisation processes [8] which will result in lithium and electron transport being facilitated. Note that the above strategies only point to address the poor charge capabilities of TiO 2 . The limitation of the low theoretical capacity still remains untouched. Lately, efforts have been taken to combine TiO 2 with a second transition metal oxide (TMO), such as tin oxide [9], iron oxide [10], manganese oxide [11], cobalt oxide [12], or molybdenum oxide [13], all of which feature extremely high theoretical capacities (700–1200 mA h g 1 ). However, these oxides are wide-bandgap semiconductors or even insulators with very low electronic conductivities, which lead to poor electron transport and thus unsatisfactory cyclability during repeated lithiation/delithiation. Simulated amorphisation recrystallisation methods have been success- fully used to spontaneously generate and characterize nano-architectures of pure TiO 2 [14,15]. In this paper, we have employed the method to synthesise lithiated TiO 2 nanosheets at 0 and 500 K. The resulting structural and microstructural features are analysed * Corresponding author. E-mail address: nkateko.rikhotso@ul.ac.za (B.N. Rikhotso). Contents lists available at ScienceDirect Optical Materials journal homepage: http://www.elsevier.com/locate/optmat https://doi.org/10.1016/j.optmat.2020.109831 Received 30 November 2018; Received in revised form 30 July 2019; Accepted 12 March 2020