A bilayer insertion of poly(oxymethylene-oxyethylene) into vanadium pentoxide xerogel: Preparation, characterization and insertion mechanism Evans Monyoncho a , Rabin Bissessur a, ⁎, Victoria Trenton b , Douglas C. Dahn b a Chemistry Department, University of Prince Edward Island. Charlottetown, PE, Canada b Physics Department, University of Prince Edward Island. Charlottetown, PE, Canada abstract article info Article history: Received 30 January 2012 Received in revised form 4 July 2012 Accepted 14 August 2012 Available online 19 September 2012 Keywords: Layered structures Ionically conductive polymers Insertion Lithium ion batteries Rechargeable batteries Nanocomposites We report a method for inserting poly(oxymethylene-oxyethylene) (POMOE) and LiCF 3 SO 3 -POMOE (Li-POMOE) complex into V 2 O 5 nH 2 O xerogel at room temperature leading to a bilayer arrangement of the POMOE-chains within the gallery spaces. This could be a significant step towards developing improved electrolyte/cathode materials for lithium/Li-ion batteries. A series of intercalates were prepared to study the effect of changing the polymer concentration on the interlayer expansion of the layered host, and to determine the optimal insertion ratio. An insertion reaction mechanism is proposed. A hydrogen-bonding network between the polymer and the V 2 O 5 framework contributes significantly to the formation of the nanocomposites. The nanocomposites showed reversible color change from red to green when subjected to electrical stimuli, thus making them good candidates for electrochromic devices. The materials were characterized by powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and impedance spectroscopy. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Intercalation chemistry provides an excellent route to combine the properties of two materials, which cannot be obtained through other methods such as organic or solid-state syntheses. Traditionally the term “intercalation” in chemistry was used to refer to a process in which a guest species (e.g Li + ion) can be reversibly inserted into a host structure such as CoO 2 . However, nowadays the term intercala- tion has been expanded to include irreversible insertion of a guest species (e.g. polymers) into hosts with layered structures [1]. There- fore, the terms intercalation and insertion will be used interchange- ably in this article. One feature of an intercalation reaction is that the guest and host experience some degree of perturbation along a spectrum, from subtle to extreme, in their geometric, chemical, elec- tronic, and optical properties [1]. Vanadium pentoxide xerogel (V 2 O 5 nH 2 O) is a host material that continues to receive researchers’ attention. This is because V 2 O 5 nH 2 O nanocomposites have various applications such as in electrochemical energy storage devices [2,3], biosensors [4], and electrochromic devices [5]. Most of the current research on V 2 O 5 nH 2 O xerogel nanocomposites is devoted to devel- oping materials that can be used in rechargeable batteries to address the ever increasing demands for renewable and portable electrical energy. V 2 O 5 nH 2 O xerogel is a good candidate for developing nano- composites because of its versatile intercalation properties. This is because the V 2 O 5 ribbons in the xerogel are linked together via hydrogen bonded water molecules. Thus, the basal distance in the xerogel is quite large and interactions between the ribbons are much weaker compared to crystalline V 2 O 5 [6]. Intercalation may occur via dipole-dipole interaction, ion-exchange, acid–base, coordi- nation, and redox reactions enabling the system to accept both neu- tral and charged guest species [7,8].V 2 O 5 nH 2 O has also shown promising redox reactions that can be utilized in lithium ion batteries. For example, Passerini et al. demonstrated that V 2 O 5 nH 2 O could be used as a cathode material that reversibly intercalates more than 3 equivalents of lithium [9]. However, the presence of intercalated water molecules in V 2 O 5 nH 2 O is of considerable concern because of the parasitic reaction of water with the anode for lithium based batte- ries [10]. Therefore, replacing water molecules with ionically conducting polymers would improve the safety of lithium batteries employing vana- dium oxide cathodes. Inclusion of ionically conducting polymers would also maintain the structural integrity of the vanadium oxide framework and promote facile movement of Li + through the interlayer spaces. Organic compounds, which can conduct alkali ions, have been under intense investigation since first reported over four decades ago by Fenton et al. [11]. In 1978 Armand et al. [12] were the first to propose that organic compounds such as polyethylene oxide (PEO) could be used as polymer electrolytes in electrochemical devices. Since then, PEO and its derivatives have been subjected to intense research to make Armand's dream a reality. Derivatives of PEO such as poly(oxymethylene-oxyethylene) (POMOE) [13] have been developed because PEO is a semi-crystalline material, which limits its ionic conduction at room temperature. The optimum room Solid State Ionics 227 (2012) 1–9 ⁎ Corresponding author. Tel.: +1 902 5660510; fax: +1 902 5660632. E-mail address: rabissessur@upei.ca (R. Bissessur). 0167-2738/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ssi.2012.08.011 Contents lists available at SciVerse ScienceDirect Solid State Ionics journal homepage: www.elsevier.com/locate/ssi