Yarn-ball-shaped P2-Na2/3Fe1/2Mn1/2O2 nanofibers prepared by magnetic-assisted electrospinning method as high-performance cathode material for Na-ion batteries

Abstract Yarn-ball-shaped P2-Na2/3Fe1/2Mn1/2O2 nanofiber cathode material is synthesized by a magnetic-assisted electrospinning method. Based on the electrospinning method, an electromagnetic-field is performed to keep the nanofibers rotating to form the yarn-ball-like architecture. XRD result indicates that the sample is a pure P2-type Na2/3Fe1/2Mn1/2O2 phase with good crystallization. SEM results show that the diameter of the balls is about 10–50 µm, and the balls are composed of nanofibers with a diameter of 200–400 nm. This special architecture is beneficial to increase the Na+ diffusion speed and tap-density of nanofiber material. Electrochemical tests show that the sample has a high discharge specific capacity of 218.6 mAh g−1 at 0.1 C rate, and exhibits good rate capability and excellent cycling performance.