In Situ Electrospinning Synthesis of N‐Doped C Nanofibers with Uniform Embedding of Mn Doped MFe1−xMnxPO4 (M = Li, Na) as a High Performance Cathode for Lithium/Sodium‐Ion Batteries

Using polyvinyl alcohol and N-rich polyacrylonitrile as carbon sources, uniform MFe1-xMnxPO4(M = Li, Na)/N-doped C nanofibers are synthesized by sol-gel pretreatment and an electrospinning method followed by calcination. The as-prepared nanofibers exhibit a 3D homogenous network with uniform distribution of MFe(1-)(x)Mn(x)PO(4)nanoparticles. The lattice distorts after Mn-doping without altering the original crystalline structure, increasing conductivity and enhancing the efficiency of Li+/Na(+)diffusion. When applied for lithium ion batteries, the optimized LiFe0.8Mn0.2PO4/C nanofibers deliver a considerable initial capacity of 169.9 mAh g(-1)with coulombic efficiency of 92.4%. It also displays the excellent cycling stability with reversible capacity of 160 mAh g(-1)after 200 cycles at 0.1 C and high rate performances with the specific capacity of 93 mAh g(-1)at 5 C. Furthermore, NaFexMn1-xPO4/N-doped C nanofibers are also synthesized by the same method for sodium-ion batteries, which exhibit an initial capacity of 134 mAh g(-1)and specific capacity of 106 mAh g(-1)at 0.1 C and 90 mAh g(-1)at 1 C after 200 cycles. Owing to the facile fabrication process, these nanofibers are promising cathodes for lithium/sodium ion batteries with excellent electrochemical performances.