McKetta Department of Chemical Engineering and Texas Materials Institute, The University of Texas at Austin, Austin, TX, 78712, USA.
Adv Mater. 2018 Sep;30(39):e1804149. doi: 10.1002/adma.201804149. Epub 2018 Aug 12.
Developing high-energy-density lithium-sulfur (Li-S) batteries relies on the design of electrode substrates that can host a high sulfur loading and still attain high electrochemical utilization. Herein, a new bifunctional cathode substrate configured with boron-carbide nanowires in situ grown on carbon nanofibers (B C@CNF) is established through a facile catalyst-assisted process. The B C nanowires acting as chemical-anchoring centers provide strong polysulfide adsorptivity, as validated by experimental data and first-principle calculations. Meanwhile, the catalytic effect of B C also accelerates the redox kinetics of polysulfide conversion, contributing to enhanced rate capability. As a result, a remarkable capacity retention of 80% after 500 cycles as well as stable cyclability at 4C rate is accomplished with the cells employing B C@CNF as a cathode substrate for sulfur. Moreover, the B C@CNF substrate enables the cathode to achieve both high sulfur content (70 wt%) and sulfur loading (10.3 mg cm ), delivering a superb areal capacity of 9 mAh cm . Additionally, Li-S pouch cells fabricated with the B C@CNF substrate are able to host a high sulfur mass of 200 mg per cathode and deliver a high discharge capacity of 125 mAh after 50 cycles.
开发高能量密度的锂硫（Li-S）电池依赖于设计能够容纳高硫负载量并仍能实现高电化学利用率的电极基底。在此，通过一种简便的催化剂辅助工艺，建立了一种新的具有原位生长在碳纤维上的碳化硼纳米线的双功能阴极基底（B C@CNF）。B C 纳米线作为化学锚定点，提供了很强的多硫化物吸附能力，这一点通过实验数据和第一性原理计算得到了验证。同时，B C 的催化作用也加速了多硫化物转化的氧化还原动力学，有助于提高倍率性能。因此，采用 B C@CNF 作为硫的阴极基底的电池在 500 次循环后具有 80%的出色容量保持率，在 4C 倍率下也具有稳定的循环性能。此外，B C@CNF 基底使阴极能够实现高硫含量（70wt%）和高硫负载量（10.3mgcm ），实现了 9mAhcm 的超高面积容量。此外，用 B C@CNF 基底制备的 Li-S 软包电池每阴极可容纳 200mg 的高硫质量，并在 50 次循环后提供 125mAh 的高放电容量。
