期刊
ACS APPLIED MATERIALS & INTERFACES
卷 12, 期 3, 页码 3670-3680出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b20490
关键词
Na3V2(PO4)(2)O2F; microsphere; carbon coating; N/P-dual-doping; DFT calculations
资金
- National Key RAMP
- D Program of China [2018YFB0905400]
- NSFC [51572151, 51772169, 51672158]
- Major Technological Innovation Project of the Hubei Science and Technology Department [2019AAA164]
Na3V2(PO4)(2)O2F (NVPOF) is attracting great interest due to its large capacity and high working voltage. However, poor electronic conductivity limits the electrochemical performance of NVPOF. Herein, we fabricate N/P-dual-doped carbon-coated NVPOF microspheres (labeled as NVPOF@P/N/C) via a hydrothermal process followed by heat treatment. This microsphere-structured NVPOF@P/N/C composite has a relatively high tap density of 1.22 g/cm(3). TEM and XPS results reveal that the dual-doped carbon layer is tightly coated on the NVPOF surface due to the bridging effect of P and has a good protective effect on NVPOF. Density functional theory (DFT) calculations confirm that a N/P-dual-doped carbon layer is advantageous to achieve higher electronic conductivity and lower migration activation energy than those of the undoped and single N- or P-doped carbon layer. As a cathode material for a sodium-ion battery (SIB), NVPOF@P/N/C exhibits high capacity (128 mAh/g at 0.5 C and 122 mAh/g at 2 C) and ultralong cycle performance (only 0.037% capacity fading rate per cycle in 500 cycles at 2 C). We believe that the NVPOF@P/N/C composite is appealing for high- performance SIBs with large energy density.
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