Dicarboxylate CaC₈H₄O₄ as a high-performance anode for Li-ion batteries

Currently, many organic materials are being considered as electrode materials and display good electrochemical behavior. However, the most critical issues related to the wide use of organic electrodes are their low thermal stability and poor cycling performance due to their high solubility in electrolytes. Focusing on one of the most conventional carboxylate organic materials, namely lithium terephthalate Li₂C₈H₄O₄, we tackle these typical disadvantages via modifying its molecular structure by cation substitution. CaC₈H₄O₄ and Al₂(C₈H₄O₄)₃ are prepared via a facile cation exchange reaction. Of these, CaC₈H₄O₄ presents the best cycling performance with thermal stability up to 570 ℃ and capacity of 399 mA·h·g^-1, without any capacity decay in the voltage window of 0.005–3.0 V. The molecular, crystal structure, and morphology of CaC₈H₄O₄ are retained during cycling. This cation-substitution strategy brings new perspectives in the synthesis of new materials as well as broadening the applications of organic materials in Li/Na-ion batteries.