Mu Jiawei, Jiang Helong, Yu Miao, Gu Shenghan, He Gaohong, Dai Yan, Li Xiangcun
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China.
ACS Appl Mater Interfaces. 2022 May 10. doi: 10.1021/acsami.2c03160.
Lithium-sulfur batteries stand out as the next-generation batteries because of their high energy density and low cost. However, the shuttle effect of lithium polysulfides (LiPSs), growth of lithium dendrites, and overuse of lithium resources still hinder their further application. To address these problems, we constructed a porous network structure in which Sn is melted and coated on a frame that has a carbon nanotube (CNT) core and a nitrogen-doped carbon (NC) coating as cross-linking shell (CNT@NC@Sn). This hierarchically porous membrane electrode, which has an ultrahigh porosity of approximately 90%, works as a matrix to strengthen the conductivity of Li and electrons and provides enough space for the conversion between sulfur and LiPSs. Moreover, the in situ thin coating of Sn not only promotes the adsorption and catalytic conversion of LiPSs but also provides lithiophilic binding sites and induces uniform lithium deposition. Thus, the thiophilic-lithiophilic porous membrane electrode with lithium loaded on the frame (in the form of Sn-Li alloy) by electroplating can replace lithium sheets, reduce the use of Li, and improve the safety performance of the battery. Additionally, these dual-functional membranes boost the reaction kinetics and conductivity of the cathode by dispersing the sulfur slurry in the porous membrane framework. As a result, the lithium-sulfur full battery assembled with the CNT@NC@Sn integrated membrane electrode exhibits stable cycling with a reversible capacity of 617.1 mAh g after 200 cycles at 1 . The capacity decay rate per cycle is 0.105%, and the N/P ratio is as low as 2.98.
锂硫电池因其高能量密度和低成本而成为下一代电池。然而，多硫化锂（LiPSs）的穿梭效应、锂枝晶的生长以及锂资源的过度使用仍然阻碍了它们的进一步应用。为了解决这些问题，我们构建了一种多孔网络结构，其中锡被熔化并涂覆在一个框架上，该框架具有碳纳米管（CNT）核心和作为交联壳的氮掺杂碳（NC）涂层（CNT@NC@Sn）。这种具有约90%超高孔隙率的分级多孔膜电极，作为增强锂和电子导电性的基质，并为硫和LiPSs之间的转化提供足够的空间。此外，锡的原位薄涂层不仅促进了LiPSs的吸附和催化转化，还提供了亲锂结合位点并诱导均匀的锂沉积。因此，通过电镀在框架上负载锂（以Sn-Li合金形式）的亲硫-亲锂多孔膜电极可以替代锂片，减少锂的使用，并提高电池的安全性能。此外，这些双功能膜通过将硫浆料分散在多孔膜框架中，提高了阴极的反应动力学和导电性。结果，采用CNT@NC@Sn集成膜电极组装的锂硫全电池在1时经过200次循环后表现出稳定的循环性能，可逆容量为617.1 mAh g 。每循环的容量衰减率为0.105%，N/P比低至2.98。
