Modulating molecular and electronic structures of organic material through an electron-rich heterocyclic polymer strategy for high-performance anodic lithium storage

Organic anode materials are promising for lithium-ion batteries due to electrochemical performance tunability, cost-effectiveness, and sustainability. However, relatively high operating potential, limited redox sites, poor electrical conductivity, and high solubility limit their practical applications. To address these limitations, a thiophene-fused polymer (PTP) is designed through an electron-rich heterocyclic polymer strategy to modulate its molecular and electronic structures, achieving lowered operating potential, high capacity, good rate capability, and long cycle lifespan, even under high-temperature conditions. In an organic lithium half-cell at room temperature, PTP delivers capacities of 601.0 and 289.0 mAh g −1 at 1.0 and 5.0 A g −1 , respectively. It maintains a capacity of 161.0 mAh g −1 after 10,000 cycles at 5.0 A g −1 , corresponding to an 84% capacity retention. Combined in situ Raman, ex situ XPS, FT-IR, and theoretical simulations reveal a lithium storage mechanism involving multi-site, multi-electron transfer redox reactions at C N and thiophene rings within the conjugated molecular skeleton. When the temperature is elevated to 60 °C, PTP achieves an ultra-high specific capacity of 1206.0 mAh g −1 at 1.0 A g −1 due to the reduced charge-transfer and ion-transport resistance caused by high temperature. The PTP also shows good full-battery performance for practical applications.