Stable, high rate capable, benzoquinone - thiophene co-polymer electrode for non-aqueous lithium-ion and zinc-ion batteries

Organic molecules and their derivates have evolved as efficient electrode materials for metal ion batteries due to the flexibility in design and good theoretical capacities. However, issues such as high solubility in battery solvents/electrolytes and low intrinsic electronic conductivity hinder their widespread use. In the present study, a carbonyl-enriched copolymer of quinone and thiophene (PTh-BQ) synthesized by a facile preparation strategy, is explored as an electrode material in non-aqueous lithium-ion and zinc-ion batteries. The incorporation of quinone units in the polythiophene chains enhances its charge storage properties. The polymer delivers a steady capacity of around 137 mAhg⁻¹ at 1 Ag⁻¹ with a coulombic efficiency of 99.9 % and a capacity retention of 83 % after 5000 cycles in lithium-ion batteries. For zinc-ion batteries, a stable capacity of 71 mAhg⁻¹ at 5Ag⁻¹ and 43 mAhg⁻¹ at a high current density of 10 Ag⁻¹ up to 10,000 cycles with almost 100 % capacity retention is observed. Participation of both thiophene and quinone groups in metal ion storage is understood using X-ray photoelectron and FT – IR spectroscopic studies. The current research promotes a convenient and promising way to develop thiophene-based polymer electrodes and opens a new avenue of designing conjugated organic polymers for energy storage.