Graphene–Li2S–Carbon Nanocomposite for Lithium–Sulfur Batteries

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• 作者：Feixiang Wu ; Jung Tae Lee ; Enbo Zhao ; Bao Zhang ; Gleb Yushin
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：January 26, 2016
• 年：2016
• 卷：10
• 期：1
• 页码：1333-1340
• 全文大小：470K
• ISSN：1936-086X

文摘

Lithium sulfide (Li₂S) with a high theoretical specific capacity of 1166mAh g^–1 is a promising cathode material for next-generation Li–S batteries with high specific energy. However, low conductivity of Li₂S and polysulfide dissolution during cycling are known to limit the rate performance and cycle life of these batteries. Here, we report on the successful development and application of a nanocomposite cathode comprising graphene covered by Li₂S nanoparticles and protected from undesirable interactions with electrolytes. We used a modification of our previously reported low cost, scalable, and high-throughput solution-based method to deposit Li₂S on graphene. A dropwise infiltration allowed us to keep the size of the heterogeneously nucleated Li₂S particles smaller and more uniform than what we previously achieved. This, in turn, increased capacity utilization and contributed to improved rate performance and stability. The use of a highly conductive graphene backbone further increased cell rate performance. A synergetic combination of a protective layer vapor-deposited on the material during synthesis and in situ formed protective surface layer allowed us to retain ～97% of the initial capacity of ～1040 mAh g_s^–1 at C/2 after over 700 cycles in the assembled cells. The achieved combination of high rate performance and ultrahigh stability is very promising.