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Na+ intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling

2015; Nature Portfolio; Volume: 6; Issue: 1 Linguagem: Inglês

10.1038/ncomms7929

2041-1723

Chaoji Chen, Yanwei Wen, Xianluo Hu, Xiulei Ji, Mengyu Yan, Liqiang Mai, Pei Hu, Bin Shan, Yunhui Huang,

Graphene research and applications

Sodium-ion batteries are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to develop an anode with superior long-term cycling stability and high-rate capability. Here we demonstrate that the Na+ intercalation pseudocapacitance in TiO2/graphene nanocomposites enables high-rate capability and long cycle life in a sodium-ion battery. This hybrid electrode exhibits a specific capacity of above 90 mA h g−1 at 12,000 mA g−1 (∼36 C). The capacity is highly reversible for more than 4,000 cycles, the longest demonstrated cyclability to date. First-principle calculations demonstrate that the intimate integration of graphene with TiO2 reduces the diffusion energy barrier, thus enhancing the Na+ intercalation pseudocapacitive process. The Na-ion intercalation pseudocapacitance enabled by tailor-deigned nanostructures represents a promising strategy for developing electrode materials with high power density and long cycle life. There are intensive efforts in developing anode materials for sodium-ion batteries. Here, the authors present a graphene-titanium dioxide composite as an anode material and show that sodium ion intercalation pseudocapacitance charge storage leads to excellent electrochemical properties.