Northeastern University , Department of Mechanical and Industrial Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115-5005, United States.
ACS Appl Mater Interfaces. 2017 May 3;9(17):14801-14807. doi: 10.1021/acsami.7b01205. Epub 2017 Apr 20.
Lithium-sulfur battery (LSB) as one of the most promising energy storage devices suffers from poor conductivity of sulfur and fast capacity decay triggered by the dissolution of polysulfides. In this work, functionalized carbonized mesoporous wood fiber (f-CMWF) is employed as a host to accommodate sulfur for the first time. Natural wood microfiber has unique hierarchical and mesoporous structure, which is well-maintained after carbonization. With such a hierarchical mesoporous structure, a high sulfur loading of 76 wt % is achieved in CMWF electrodes. The pore size of CMWF is tunable by atomic layer deposition (ALD) of a 5 nm AlO coating to form the f-CMWF. Such a thin layer slightly decreases the sulfur loading to 70%, but it remarkably promotes the cyclic stability of sulfur cathode, which delivers an initial capacity of 1115 mAh g, and maintains a reversible capacity of 859 mAh g for 450 cycles, corresponding to a slow capacity decay rate of 0.046% per cycle. More importantly, natural wood microfiber is first used as a raw material for sulfur encapsulating. This work is also critical for using low cost and mesoporous biomass carbon as bifunctional scaffold for LSB.
锂硫电池（LSB）作为最有前途的储能设备之一，但其导电性差和多硫化物溶解引发的快速容量衰减问题仍亟待解决。在这项工作中，功能化碳化介孔木纤维（f-CMWF）首次被用作容纳硫的主体。天然木纤维具有独特的分级和介孔结构，碳化后仍能很好地保持。具有这种分级介孔结构，CMWF 电极中实现了高达 76wt%的高硫负载量。通过原子层沉积（ALD）的 5nmAlO 涂层对 CMWF 的孔径进行调谐，形成 f-CMWF。这样的薄层略微降低了硫的负载量至 70%，但却显著提高了硫正极的循环稳定性，其初始容量为 1115mAhg-1，在 450 次循环中保持 859mAhg-1的可逆容量，对应的容量衰减率为 0.046%/循环。更重要的是，天然木纤维首次被用作硫封装的原料。这项工作对于使用低成本和介孔生物质碳作为 LSB 的双功能支架也具有重要意义。
