空心炭球在室温钠硫电池中的研究进展

Recent progress on the design of hollow carbon spheres to host sulfur in room-temperature sodium-sulfur batteries

  • 摘要: 室温钠硫(RT-Na/S)电池具有理论比容量高(1 675 mAh/g)、能量密度大(1 276 Wh/kg)以及钠、硫储量丰富且成本低等优势,在智能电网等大规模储能领域具有广阔的应用前景。然而,RT-Na/S电池仍然面临着诸多问题如硫导电性差、放电过程中体积膨胀以及中间态多硫化钠溶解穿梭等,严重地阻碍了电池性能的发挥和实际应用。近年来,空心炭球由于其独特的物理化学性质,在一定程度上能有效地解决硫正极中特别是多硫化钠的溶解穿梭等问题,有效提高了电池的性能。本文介绍了近年来空心炭球基材料的构筑及其在RT-Na/S电池中的应用,重点讨论了孔结构调控、掺杂基团与功能组分修饰对缓解"穿梭效应"及提高电池性能的影响,并对未来的发展进行了展望。

     

    Abstract: Room-temperature sodium-sulfur (RT-Na/S) batteries are an important class of rechargeable batteries with a high theoretical capacity of 1 675 mAh g-1 and energy density up to 1 276 Wh kg-1 (based on Na2S). They are recognized as attractive next-generation high-energy-density devices for large-scale energy storage owing to the abundance and low cost of sodium and sulfur. However, similar to the working principle in lithium-sulfur batteries, they suffer from some basic problems such as the poor conductivity of elemental sulfur, a large volume change during charge-discharge cycling and a serious shuttle effect caused by sodium polysulfide dissolution. Moreover, the shuttle effect and volume change seem more pronounced in RT-Na/S batteries, which further decreases their performance and seriously hinders the progress towards their practical application. A fast growth in designing porous carbons, especially hollow carbon spheres (HCSs), as a sulfur host to address these problems has been seen in recent years, due to their unique structural features such as a large void space, a permeable shell, and simple functionalization. This review summarizes recent progress in HCS-based materials as the sulfur hosts in RT-Na/S batteries. Beginning with a brief introduction to RT-Na/S batteries, carbon hosts and design strategies for preparing HCSs, particular emphasis is placed on manipulating the pore structure, heteroatom doping and decoration with metal species with the aim of alleviating the "shuttle effect" and thus improving the performance. Finally, perspectives on current challenges and future research directions are discussed.

     

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