Abstract :
[en] The development of Li-ion batteries for the new flexible technologies should also consider environment and safety issues. Therefore, this research focused on developing an aqueous waterbased process for the preparation of free-standing, CNT-free and flexible Li4Ti5O12 (LTO) electrodes, where LTO itself was also obtained through an aqueous route. The electrodes contain carbon black, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) 500 or 6000 g/mol. The SEM and IR-ATR analyses confirmed a good distribution of all components. 2 wt% PEG 6000 or 3 wt% PEG 500 with respect to LTO were the optimum ratios to obtain free-standing flexible electrodes. The suspensions were studied by rheological analysis: the system was found to be stable (G’ modulus above G’’ modulus) and the role of the polymers and carbon in the suspensions has been investigated by viscosity measurements. Excellent electrochemical performances (up to 157mAh/g at 1C rate) were obtained for PEG6000-based current-collector-free electrodes. Mild mechanical stress applied to the electrodes before the measurements allowed to enhance the performances, which could be related to the creation of tiny cracks which led to better penetration of the electrolyte in the electrode.
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