Ultrafast Charging Enabled by Soft Ion Channels on Layered Transition Oxide Cathodes in Aqueous Li-Ion Batteries

Abstract

High-power battery systems are essential for electric vehicles and grid stability, yet their development hinges on optimizing ion transport at the electrode-electrolyte interface to minimize Li+ migration barriers and suppress parasitic reactions. Here, we demonstrated a molecularly engineered interfacial ion channel on LiCoO2 (LCO) using amphiphilic lithium dodecyl sulfate (DS), which enabled ultrafast and durable performance in aqueous media. The DS molecules assembled into dynamic interfacial architectures that facilitated efficient Li+ transport, delivering remarkable rate capability of similar to 82 mAh g-1 at a 10C rate for 1000 cycles and similar to 80 mAh g-1 at 15C for 500 cycles with Coulombic efficiencies of 99.49% and 99.51%, respectively. In situ electrochemical infrared spectroscopy revealed that DS adopted a sulfate-headgroup-downward orientation predominantly, while voltage polarization drove incorporation of upward-oriented molecules from the bulk electrolyte solution. Density functional theory (DFT) calculations showed that the downward configuration lowers Li+ extraction barriers during charging, while the mixed orientation facilitates Li+ insertion during discharging. Experimentally, the well-designed DS layer increased Li+ mobility by nearly an order of magnitude compared to the DS-free system. These synergistic effects underpin the exceptional rate performance and highlight the effectiveness of molecularly engineered ion channels in enabling high-power Li-ion batteries.