Polydopamine is gaining much interest in lithium secondary batteries (LSBs) due to its ability to enhance the electrochemical characteristics of the various LSB systems. However, the commercialization of polydopamine is being delayed due to long production time. Nevertheless, recent studies have showed that polydopamine can be formed during galvanostatic charge and discharge of unit cells with dopamine. Hence we adopt this methodology to study the effects of dopamine as an electrolyte additive on the electrochemical performance of LSBs. The effect of the dopamine additive is characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The cycle performance of coin cells containing dopamine in the electrolyte at different temperatures are examined by changing cut-off voltages together.

The coin cells having 0.1 wt.% of dopamine exhibited an enhanced cycle performance at both high voltage (3.0~4.5V vs. Li/Li+, 25^oC, C/2 rate) and elevated temperature (3.0~4.3V vs. Li/Li+, 55^oC, C/2 rate). The improvement in the cycling performance is attributed to the suppression of transition metal dissolution in the cathode as well as the decomposition of both solvent and salt in the electrolyte due to the formation of the polydopamine on the surface of the cathode during the galvanostatic charge and discharge.

 Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977) and by the Sebang Global Battery.

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