Fused Heteroaromatic Organic Compounds for High-Power Electrodes of Rechargeable Lithium Batteries

摘要

Organic redox compounds are emerging electrode materials for rechargeable lithium batteries. However, their electrically insulating nature plagues efficient charge transport within the electroactive bulk. Alternative to the popular solution of elaborating nanocomposite materials, herein we report on a molecular-level engineering strategy towards high-power organic electrode materials with multi-electron reactions. Systematic comparisons of anthraquinone analogues incorporating fused heteroaromatic structures as cathode materials in rechargeable lithium batteries reveal that the judicious incorporation of heteroaromatics improves the cell performance in terms of specific gravimetric capacity, working potential, rate capability, and cyclability. Combination studies with morphological observation, electrochemical impedance characterization, and theoretical modeling provide insight into the advantage of heteroaromatic building blocks. In particular, benzofuro[5,6-b]furan-4,8-dione (BFFD) bearing furan moeities shows a reversible capacity of 181 mAh g~(-1) when charged/discharged at 100C, corresponding to a power density of 29.8 kW kg~(-1). These results have pointed to a general design route of high-rate organic electrode materials by rational functionalization of redox compounds with appropriate heteroaromatic units as versatile structural tools.