Evaluation of Flexible Li4Ti5O12 Anode Electrodes Using Water-Based Binder for Li-Ion Batteries

Abstract

Li-ion batteries are today essential for portable electronic devices as a main power source. Flexible Li-ion batteries have attracted great attention and could be very useful in the emerging fields of flexible, wearable, implantable and bendable electronic devices. Nano-fibrillated cellulose (NFC), with a high aspect ratio (length/diameter) of the nanofibrils, has shown to be a promising binder material for flexible Li-ion batteries [i] [ii]. As a reinforcement component, it gives flexible electrodes good mechanical properties. In addition, the process of making the flexible electrodes is water-based, eliminating the toxicity problem of using conventional poly(vinylidene fluoride) (PVDF) as binder. However, capacity fading limits the stability of the flexible electrodes during repeated cycling. Side reactions on the graphite negative electrodes could be the reason for the capacity loss. Li4Ti5O12(LTO), with a high potential of 1.55 V versus Li metal, could be an alternative to graphite for flexible negative electrodes, reducing the reactivity with the electrolyte. In this work, the electrochemical performance, such as specific capacity and columbic efficiency (CE), and mechanical properties of flexible LTO anode electrodes using NFC as binder are investigated. Fig 1 shows the photograph of LTO electrode, illustrating the flexibility. Fig. 1 Photograph of flexible Li4Ti5O12 negative electrode. [i] S.Leijonmarck, et al. Flexible nano-paper-based positive electrodes for Li-ion batteries-Preparation process and properties, Nano Energy, 2013, 2, 794–800. [ii] S.Leijonmarck, et al. Single-paper flexible Li-ion battery cells through a paper-making process based on nano-fibrillated cellulose, Journal of Materials Chemistry A, 2013, 1, 4671-4677. Figure 1