Hermetically Coated and Well-Separated Co3O4 Nanophase within Porous Graphitic Carbon Nanosheets: Synthesis, Confinement Effect, and Improved Lithium-Storage Capacity and Durability

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• 作者：Jingfei Zhang ; Wangyu Ren ; Yunyun Zhou ; Pei Li ; Prof. Lin Xu ; Prof. Dongmei Sun ; Prof. Ping Wu ; Prof. Yiming Zhou and Prof. Yawen Tang
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：July 4, 2016
• 年：2016
• 卷：22
• 期：28
• 页码：9599-9606
• 全文大小：4298K
• ISSN：1521-3765

文摘

Considerable lithium-driven volume changes and loss of crystallinity on cycling have impeded the sustainable use of transition metal oxides (MOs) as attractive anode materials for advanced lithium-ion batteries that have almost six times the capacity of carbon per unit volume. Herein, Co₃O₄ was used as a model MO in a facile process involving two pyrolysis steps for in situ encapsulation of nanosized MO in porous two-dimensional graphitic carbon nanosheets (2D-GCNs) with high surface areas and abundant active sites to overcome the above-mentioned problems. The proposed method is inexpensive, industrially scalable, and easy to operate with a high yield. TEM revealed that the encaged Co₃O₄ is well separated and uniformly dispersed with surrounding onionlike graphitic layers. By taking advantage of the high electronic conductivity and confinement effect of the surrounding 2D-GCNs, a hierarchical GCNs-coated Co₃O₄ (Co₃O₄@GCNs) anode with 43.5 wt % entrapped active nanoparticles delivered a remarkable initial specific capacity of 1816 mAh g⁻¹ at a current density of 100 mA g⁻¹. After 50 cycles, the retained capacity is as high as 987 mAh g⁻¹. When the current density was increased to 1000 mA g⁻¹, the anode showed a capacity retention of 416 mAh g⁻¹. Enhanced reversible rate capability and prolonged cycling stability were found for Co₃O₄@GCN compared to pure GCNs and Co₃O₄. The Co₃O₄@GCNs hybrid holds promise as an efficient candidate material for anodes due to its low cost, environmentally friendly nature, high capacity, and stability.