Pyrolytic Carbon Nanosheets for Ultrafast and Ultrastable Sodium‐Ion Storage
Se Youn Cho; Minjee Kang; Jaewon Choi; Min Eui Lee; Hyeon Ji Yoon; Hae Jin Kim; Cecilia Leal; Sungho Lee; Hyoung‐Joon Jin; Young Soo Yun
文献索引：10.1002/smll.201703043
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摘要
Na‐ion cointercalation in the graphite host structure in a glyme‐based electrolyte represents a new possibility for using carbon‐based materials (CMs) as anodes for Na‐ion storage. However, local microstructures and nanoscale morphological features in CMs affect their electrochemical performances; they require intensive studies to achieve high levels of Na‐ion storage performances. Here, pyrolytic carbon nanosheets (PCNs) composed of multitudinous graphitic nanocrystals are prepared from renewable bioresources by heating. In particular, PCN‐2800 prepared by heating at 2800 °C has a distinctive sp2 carbon bonding nature, crystalline domain size of ≈44.2 Å, and high electrical conductivity of ≈320 S cm−1, presenting significantly high rate capability at 600 C (60 A g−1) and stable cycling behaviors over 40 000 cycles as an anode for Na‐ion storage. The results of this study show the unusual graphitization behaviors of a char‐type carbon precursor and exceptionally high rate and cycling performances of the resulting graphitic material, PCN‐2800, even surpassing those of supercapacitors.