鋰硫電池及石墨烯在硫電極的應用

Lithium-sulfur Battery and Applications of Graphene as Host Materials for Sulfur Cathodes

黃柏升(Bo-Sheng Huang) ； 康家豪(Jia-Hao Kang) ； 陳振興(Jenn-Shing Chen)

《化學》 76卷3期 (2018/09) Pp. 193-200

https://doi.org/10.6623/chem.201809_76(3).005

摘要

鋰硫電池(Li-S)主要組成為硫(S)為陰極（正極），鋰金屬(Li)為陽極（負極）及含鋰離子的有機電解質所組成。鋰硫電池的充放電機制，放電時，陰極的硫(S_8)先還原生成多種可溶性的長鏈狀多硫化物S_n^(2-)(4 ≤ n ≤ 8)中間產物後，再進一步和Li^+結合沉積成不溶性的固態鋰硫化物(Li_2S_2/Li_2S)。充電時，固態鋰硫化物經由多硫化物中間產物氧化生成回到原先的硫(S_8)。陽極的鋰金屬在充放電時，則進行一般溶解及沉積的金屬氧化還原反應步驟，電池陰陽極形成可逆反應。鋰硫電池以硫為活性物質，硫是一種環境友善的元素，對環境基本上沒有污染，原料成本低廉且易於回收利用，並具有高的理論能量密度等優點，具有很大開發價值的儲能電極材料。但這種基於溶解−沉積反應機制的鋰硫電池體系中仍面臨一些無法避免的問題，主要包括金屬鋰負極顯著結構的變化易產生針狀彌散的鋰金屬、硫正極材料存在的活性物質利用率低和循環性能差等缺點，限制了鋰硫電池的發展。本文簡要闡述了鋰硫電池的問題，結合近年來關於鋰／硫電池的突破進展，利用以石墨烯為複合材料主體的相關技術來改善電池的性能。

關鍵字

鋰硫電池 ； 硫 ； 陰極材料 ； 石墨烯

並列摘要

A typical rechargeable lithium-sulfur (Li-S) battery is constituted by a sulfur cathode, a lithium metal anode and a Li^+-conducting electrolyte. The Li-S cell operates by reduction of sulfur (S_8) at the cathode during the discharge to form a series of soluble polysulfides S_n^(2-) (4 ≤ n ≤ 8) that combine with Li to ultimately produce insoluble lithium sulfide (Li_2S_2/Li_2S) at the end of the discharge. On charging, Li_2S_2/Li_2S is converted back to S_8 via similar soluble polysulfide intermediates presented in the discharge process and lithium plates to the normal anode, making the cell reversible. Accordingly, rechargeable Li-S batteries have recently attracted attention due to the relative low cost of sulfur as well as the environmental friendliness and high theoretical specific energy density. Despite these favorable characteristics, their practical applications are still hampered by several serious challenges including structural charge of Li metal anode, low utilization of S cathode active materials and poor cycle stability of the cell. In this paper, we present current problems of rechargeable Li-S batteries and review some reports from recent literatures about the applications of graphene as host materials for sulfur cathodes to improve the performance of Li-S batteries.

並列關鍵字

Lithium-sulfur battery ； Sulfur ； Cathode material ； Graphene