Trace Li Pre‐Doping of Activated Carbon Cathode Enabling Accelerated Li‐Ion Transport for High‐Power Lithium‐Ion Capacitors

Rapid expansion of AI‐driven data centers demands energy storage systems that simultaneously deliver high power, safety, and practical scalability. Lithium‐ion capacitors (LICs) are attractive candidates; however, their performance is fundamentally constrained by inefficient Li pre‐doping and pore blockage in activated carbon (AC) cathodes. In this study, ultralow‐level Li pre‐doping, far below conventional loading thresholds, is demonstrated to induce substantial performance enhancement without compromising the intrinsic porous structure of AC. Through a simple Li‐based surface modification followed by controlled thermal conversion, an ultrathin and uniformly distributed lithiophilic layer is introduced, where Li 2 CO 3 is identified as the most effective phase for high‐power operation. Remarkably, even trace Li incorporation, undetectable by conventional spectroscopic techniques, significantly enhances Li‐ion transport, as supported by molecular dynamics simulations. This minimal yet effective surface modification reduces polarization while improving both capacity and rate capability. Consequently, pouch‐type full cells exhibit enhanced high‐power performance, increased capacity, and stable cycling behavior under practical operating conditions. These findings establish Li pre‐doping as a scalable and cost‐effective strategy for engineering high‐performance LIC cathodes and provide a viable pathway toward next‐generation energy storage systems for AI‐driven infrastructure.