Sulphur-doped reduced graphene oxide sponges as high-performance free-standing anodes for K-ion storage

By Jinliang Li, W. Qin, Junpeng Xie, Hang Lei, Yongqiang Zhu, Wenyu Huang, Xiang-Nan Xu, Zhijuan Zhao, Wenjie Mai. Nano Energy, 2018

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Abstract Due to the large radius of K-ion, K-ion batteries (KIBs) involving K-ion insertion and extraction processes generally exhibit an insufficient cycle life and poor rate performance. In this work, sulphur-doped reduced graphene oxide (S-RGO) sponges, which are used as free-standing anodes for KIBs, are obtained via simple freeze-drying of graphene oxide solution and subsequent thermal treatment in sulphur steam. After sulphur doping, our S-RGO sponges deliver preeminent electrochemical performance. Such free-standing electrodes exhibit high K-ion storage capacity of 361 mAh g −1 at 50 mA g −1 over 50 cycles. Furthermore, even at a high current density of 1 A g −1 , they also display a highly stabile K-ion storage with a capacity of 229 mAh g −1 over 500 cycles, which outperforms all previously reported carbon-based materials for KIBs. Such preeminent performance is attributed to the S-RGO sponges’ unique conductive structure and the sulphur doping, which effectively enhance the insertion of large K ions. We also utilize ex-situ XPS to illuminate the reaction process of our sample during potassiation/depotassiation and highlight the role of sulphur doping in improving K-ion storage performance.

Subfields: Automotive Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/79a66cbf77805aeac89a0f268d9d87cddf2726f2