Niu Yubin, Xu Maowen, Dai Chunlong, Shen Bolei, Li Chang Ming
Institute for Clean Energy & Advanced Materials, Faculty of Materials and Energy, Southwest University, Chongqing 400715, P. R. China.
Phys Chem Chem Phys. 2017 Jul 5;19(26):17270-17277. doi: 10.1039/c7cp02483e.
NaFe(PO) is one of the intensively investigated polyanionic compounds and has shown high rate discharge capacity, but its relatively low electronic conductivity hampers the high performance of the batteries. Herein for the first time we report new graphene wrapped NaFe(PO) composite nanofibers (NFPO@C@rGO) made from electrospinning for cathodes of SIBs to achieve an even higher performance with a highly stable discharge capacity of ∼99 mA h g at a current density of 40 mA g after 320 cycles, which is 1.6 times higher than that of the pristine NaFe(PO) (NFPO@C) composite. In particular, the NFPO@C@rGO composite cathode exhibits an even higher discharge rate capacity of ∼53.9 mA h g at a current density of 1280 mA g (11C) than that of ∼40 mA h g at a current density of 1100 mA g (9.4C) for the reported best high discharge rate performance of NFPO. The superior cycling and high rate capability are attributed to the unique spinning vein fiber based porous structure offering a good intimate contact between NFPO@C and graphene for great electronic conductivity, fast ionic transport, a large reaction surface and a strong solid structure preventing collapse during cycling, thus achieving a high rate discharge performance and high cycling stability.
磷酸铁钠（NaFe(PO)）是一种受到深入研究的聚阴离子化合物，具有较高的倍率放电容量，但其相对较低的电子电导率阻碍了电池的高性能表现。在此，我们首次报道了通过静电纺丝制备的新型石墨烯包覆磷酸铁钠（NaFe(PO)）复合纳米纤维（NFPO@C@rGO），用于钠离子电池的阴极，在电流密度为40 mA g时经过320次循环后实现了更高的性能，具有约99 mA h g的高度稳定放电容量，这比原始的磷酸铁钠（NaFe(PO)）（NFPO@C）复合材料高出1.6倍。特别是，NFPO@C@rGO复合阴极在电流密度为1280 mA g（11C）时表现出约53.9 mA h g的更高倍率放电容量，高于报道的磷酸铁钠最佳高倍率性能在电流密度为1100 mA g（9.4C）时约40 mA h g的放电容量。优异的循环性能和高倍率性能归因于独特的基于纺丝脉络纤维的多孔结构，该结构为NFPO@C和石墨烯之间提供了良好的紧密接触，实现了良好的电子导电性、快速的离子传输、较大的反应表面以及在循环过程中防止坍塌的坚固结构，从而实现了高倍率放电性能和高循环稳定性。
