A phosphorene-graphene hybrid material as a high-capacity anode for sodium-ion batteries.
Sodium-ion batteries have recently attracted significant attention as an alternative to lithium-ion batteries because sodium sources do not present the geopolitical issues that lithium sources might. Although recent reports on cathode materials for sodium-ion batteries have demonstrated performances comparable to their lithium-ion counterparts, the major scientific challenge for a competitive sodium-ion battery technology is to develop viable anode materials. Here we show that a hybrid material made out of a few phosphorene layers sandwiched between graphene layers shows a specific capacity of 2,440 mA h g(-1) (calculated using the mass of phosphorus only) at a current density of 0.05 A g(-1) and an 83% capacity retention after 100 cycles while operating between 0 and 1.5 V. Using in situ transmission electron microscopy and ex situ X-ray diffraction techniques, we explain the large capacity of our anode through a dual mechanism of intercalation of sodium ions along the x axis of the phosphorene layers followed by the formation of a Na3P alloy. The presence of graphene layers in the hybrid material works as a mechanical backbone and an electrical highway, ensuring that a suitable elastic buffer space accommodates the anisotropic expansion of phosphorene layers along the y and z axial directions for stable cycling operation.
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Jie
J
Sun
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Hyun-Wook
http://orcid.org/0000-0001-9074-1619
HW
Lee
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Mauro
M
Pasta
Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
Hongtao
H
Yuan
Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
Guangyuan
G
Zheng
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Yongming
Y
Sun
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
Yuzhang
Y
Li
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
Yi
Y
Cui