Towards Ultrahigh Capacity and High Cycling Stability Lithium-Conducting Polymer Batteries by In Situ Construction of Nanostructured Porous Cathodes

Conducting polymers (CPs) have long been studied as cathode materials for lithium-ion batteries, but the low doping level (maximum: 30-50% or even lower) and poor cycling stability limit their applications. Herein, we have developed a method of nanoporeconfined in situ electropolymerization to prepare nanostructured polythiophene-type porous cathodes, achieving significantly improved doping availability and long cycle life. It was verified that the nanosized polymer formed in situ and loose porous structure are conducive to the doping reaction and maintain high electrochemical stability. The constructed thieno[3,2-b]thiophene (TtTP)/active carbon cathode delivers an ultrahigh reversible capacity of 309.2 mAh g-1 (doping level up to 80.9%) along with an ultrahigh energy density of 1252.3 Wh Kg-1, and an ultrahigh rate capability (172.4 mAh g-1 at 30 A g-1), which far exceed all the CPs and even all the p-type organic cathode materials reported. Moreover, an excellent long cycle life of 2000 cycles at 5 A g-1 is also revealed, which is a new record for CPs-based cathode materials in nonaqueous lithium-ion batteries. Our method provides an effective strategy to improve the doping level and cycling stability of CP-based cathode materials.