College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid , China Three Gorges University , 8 Daxue Road , Yichang , Hubei 443002 , China.
School of Chemical Engineering & Light Industry , Guangdong University of Technology , Guangzhou , Guangdong 510006 , China.
ACS Appl Mater Interfaces. 2020 Jan 22;12(3):3670-3680. doi: 10.1021/acsami.9b20490. Epub 2020 Jan 8.
NaV(PO)OF (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. 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.
由于具有较大的容量和较高的工作电压，NaV(PO)OF（NVPOF）引起了人们的极大兴趣。然而，较差的电子导电性限制了 NVPOF 的电化学性能。在此，我们通过水热法和随后的热处理制备了 N/P 双掺杂碳包覆的 NVPOF 微球（标记为 NVPOF@P/N/C）。这种具有微球结构的 NVPOF@P/N/C 复合材料具有相对较高的振实密度为 1.22 g/cm。TEM 和 XPS 结果表明，由于 P 的桥接作用，双掺杂碳层紧密包覆在 NVPOF 表面上，并对 NVPOF 具有良好的保护作用。密度泛函理论（DFT）计算证实，与未掺杂和单 N 或 P 掺杂碳层相比，N/P 双掺杂碳层有利于实现更高的电子电导率和更低的迁移活化能。作为钠离子电池（SIB）的正极材料，NVPOF@P/N/C 表现出高容量（在 0.5 C 时为 128 mAh/g，在 2 C 时为 122 mAh/g）和超长循环性能（在 2 C 时 500 次循环中仅为 0.037%的容量衰减率）。我们相信，NVPOF@P/N/C 复合材料很有吸引力，可用于具有高能量密度的高性能 SIB。
