Phenylpyridine Dicarboxylate as Highly Efficient Organic Anode for Na-Ion Batteries

The sodium-ion battery (SIB) has the potential to be the next-generation rechargeable system, utilizing cheap and abundant sodium material. One of the key obstacles to sodium batteries is the lack of efficient and stable anode materials. Compared with traditional inorganic electrode materials, organic materials are more attractive because of their easier sodium transport accessibility and the diversities of organic frameworks and functional groups. In this work, two molecules (Na-CPN and Na-CPP) were synthesized and used as anode materials for SIBs. Structurally, the two compounds are isomers, and they are distinguished by the position of N atoms in phenylpyridine. Na-CPP showed a high reversible capacity of 197 mAh g^-1 , and its capacity could maintain 99.1 % of its initial value even after 350 cycles of 100 mA g^-1 . Moreover, after going through 1200 cycles at a current density of 5 C, the Na-CPP electrode still retained a capacity rate of 89.9 %. In contrast, Na-CPN exhibited inferior capacity and rate performance because of its larger polarization, particle size, and charge transport resistance.