Designing High-Rate and High-Capacity Lithium Metal Anodes: Unveiling Critical Role of Carbon Nanotube Structure

Strategic material selection is critical for designing high-performance energy-storage systems. This study reveals that the intrinsic structure of carbon nanotubes (CNTs), rather than modification, plays a decisive role in achieving ultrahigh capacity and stability. Using CNT selection as a design strategy, a mesoporous Li host is developed that enables an exceptional areal capacity of 90 mAh cm^-2, long-term cycling stability exceeding 2000 cycles, and operation at an ultrahigh current density of 60 mA cm^-2 in symmetric cells. Comprehensive CNT characterization reveals significant differences in diameter, wall number, length, surface chemistry, and assembly behavior, all of which critically influence the lithiophilicity, mechanical integrity, and electrolyte permeability. These factors govern the Li deposition behavior, highlighting the importance of selecting CNTs according to their intrinsic properties rather than relying on post-processing modifications. The anode design is validated in a full Li battery cell using a commercial cathode, achieving an areal capacity of 1.5 mAh cm^-2, an 800-cycle lifetime, and stable operation at a current density of 1.5 mA cm^-2, significantly surpassing conventional benchmarks. This work establishes the fundamental role of CNT structure-property relationships in Li-metal anode design, offering a pathway for simplified processing, enhanced performance, and more reliable next-generation Li-metal batteries.