Constructing Structural Isomers to Reveal and Enhance Lithium Storage in a Conducting Polymer

Abstract

AbstractOrganic electrodes have gained great interest for batteries. Conducting polymers have the merits of high conductivity, and hence are attempted as electrode materials in batteries as soon as their discoveries. However, conducting polymers showe poor electrochemical performance and are baring vague charge storage mechanisms. Here, a strategy is reported to reveal the charge storage mechanisms of conducting polymers by constructing isomers and using polypyridines as a proof‐of‐concept. Polypyridines are rarely studied and its redox activity is still not clear. The results indicate that every pyridine ring can accept one electron and the dimer unit with adjacent C═N groups can gain one more electron through chelation effects with Li ions. The electron transferred number and the chelation effects can be quantified by the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectroscopy and verified by density functional theory (DFT) calculations. As a result, one of the polypyridine isomers delivers the highest capacity of 504 mAh g−1 after deducting the contribution of conductive additives. This work provides a universal way to reveal the charge storage mechanism and highlights the significance of adjacent active centers to form chelation with Li ions and hence enhance the performance of organic batteries.