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 Li2CO3 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.