| 초록 |
Although the lots of research have improved the performance of lithium-ion batteries, their cycle stability and energy density at high rate condition remain insufficient. Recently, Silicon-based active materials, exhibiting much higher theoretical capacity than conventional graphite anode, have emerged as one of the most promising new anode materials to follow those requests. However, problems associated with the unstable evolution of a solid-electrolyte interphase (SEI) on the active anode surface still remain and these become more detrimental with increasing cycling rates. Here, we report the near fatigue-free, ultrafast, and high-power operating negative electrode employing silicide nanowires (NWs) anchored selectively to the inner surface of 3D-graphene electrodes. This design, electrically shields the electrolyte inside the electrode from an external potential load, eliminating the driving force that generates the SEI on the NW surface during lithiation. Thank to this electric control, an SEI develops firmly on the outer surface of the graphene, while the SEI-free silicide NWs enable fast electronic and ionic transport, as well as strain relaxation over 2000 cycles, with 84% capacity retention even at ultra-fast cycling (＞ 20C). |
