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Two N-substituted naphthalene tetracarboxylic diimide (NTCDI) ionic compounds, carboxylic and sulfonic sodium salts, were prepared and used as positive electrode active materials in lithium-half cells. The aim of this investigation was to assess the solubility-suppressing effect of two different negatively charged substituent groups on a redox-active organic backbone using a carbonate-based liquid electrolyte. NTCDI derivatives were obtained in high yields from reaction of naphthalene tetracarboxylic dianhydride with neutralized glycine or with neutralized taurine. They were mixed with carbon black and cycled in galvanostatic mode against lithium metal using 1M LiPF6 EC/DMC liquid electrolyte. These two NTCDI derivatives exhibit a quite stable electrochemical activity upon cycling at an average potential of 2.3V vs. Li+/Li0 giving rise to specific capacity values of 147mAh·g−1 and 113mAh·g−1 for the dicarboxylate and the disulfonate derivative, respectively. This study clearly supports the useful effect of such grafted permanent charges as a general rule on the electrochemical stability of crystallized organic materials based on the assembly of small redox-active units.
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•Synthesis of 2 naphthalene tetracarboxydiimide carboxylic and sulfonic sodium salts.•Use of these compounds as active materials for Li-ion batteries.•Reversible electrochemical activity at similar working potential for both molecules.•Very high coulombic efficiency over 50cycles for the two compounds (~99%).•Solubility limitation and electrochemical capacity retention due to grafted charges.