Department of Materials Science and Engineering, ‡Department of Mechanical Engineering, University of Maryland , College Park, Maryland 20742, United States.
Nano Lett. 2017 Jun 14;17(6):3792-3797. doi: 10.1021/acs.nanolett.7b01138. Epub 2017 May 9.
Room-temperature Na ion batteries (NIBs) have attracted great attention because of the widely available, abundant sodium resources and potentially low cost. Currently, the challenge of the NIB development is due primarily to the lack of a high-performance anode, while the Na metal anode holds great promise considering its highest specific capacity of 1165 mA h/g and lowest anodic potential. However, an uneven deposit, relatively infinite volume change, and dendritic growth upon plating/stripping cycles cause a low Coulombic efficiency, poor cycling performance, and severe safety concerns. Here, a stable Na carbonized wood (Na-wood) composite anode was fabricated via a rapid melt infusion (about 5 s) into channels of carbonized wood by capillary action. The channels function as a high-surface-area, conductive, mechanically stable skeleton, which lowers the effective current density, ensures a uniform Na nucleation, and restricts the volume change over cycles. As a result, the Na-wood composite anode exhibited flat plating/stripping profiles with smaller overpotentials and stable cycling performance over 500 h at 1.0 mA/cm in a common carbonate electrolyte system. In sharp comparison, the planar Na metal electrode showed a much shorter cycle life of 100 h under the same test conditions.
室温钠离子电池（NIBs）因其广泛存在、丰富的钠资源和潜在的低成本而受到极大关注。目前，NIB 发展的挑战主要是由于缺乏高性能的阳极，而鉴于其最高 1165 mA h/g 的比容量和最低的阳极电势，Na 金属阳极具有很大的应用前景。然而，在电镀/剥离循环过程中，不均匀的沉积、相对无限的体积变化和枝晶生长导致低库仑效率、较差的循环性能和严重的安全问题。在此，通过毛细作用将熔融的 Na 快速注入碳化木材的通道中（约 5 s），制备了一种稳定的 Na 碳化木材（Na-wood）复合阳极。通道作为一个具有高表面积、导电、机械稳定的骨架，降低了有效电流密度，确保了 Na 的均匀成核，并限制了循环过程中的体积变化。因此，Na-wood 复合阳极在碳酸盐电解质体系中以 1.0 mA/cm 的电流密度进行 500 小时的测试时，表现出了平坦的电镀/剥离曲线，具有更小的过电位和稳定的循环性能。相比之下，在相同的测试条件下，平面 Na 金属电极的循环寿命要短得多，只有 100 小时。
