Ferrocene‐Based Polymer Organic Cathode for Extreme Fast Charging Lithium‐Ion Batteries with Ultralong Lifespans

Abstract To meet the growing demand for energy storage, lithium‐ion batteries (LIBs) with fast charging capabilities has emerged as a critical technology. The electrode materials affect the rate performance significantly. Organic electrodes with structural flexibility support fast lithium‐ion transport and are considered promising candidates for fast‐charging LIBs. However, it is a challenge to create organic electrodes that can cycle steadily and reach high energy density in a few minutes. To solve this issue, accelerating the transport of electrons and lithium ions in the electrode is the key. Here, it is demonstrated that a ferrocene‐based polymer electrode (Fc‐SO₃Li) can be used as a fast‐charging organic electrode for LIBs. Thanks to its molecular architecture, LIBs with Fc‐SO₃Li show exceptional cycling stability (99.99% capacity retention after 10 000 cycles) and reach an energy density of 183 Wh kg⁻¹ in 72 seconds. Moreover, the composite material through in situ polymerization with Fc‐SO₃Li and 50 wt % carbon nanotube (denoted as Fc‐SO₃Li‐CNT50) achieved optimized electron and ion transport pathways. After 10 000 cycles at a high current density of 50C, it delivered a high energy density of 304 Wh kg⁻¹. This study provides valuable insights into designing cathode materials for LIBs that combine high power and ultralong cycle life.