Li(Na)2FeSiO4/C hybrid nanotubes: promising anode materials for lithium/sodium ion batteries

Li2FeSiO4 is a superior cathode material for lithium ion batteries (LIBs) owing to its high capacity, low cost, and superior stability. Exhilaratingly, the material also exhibits the desired electrochemical performance as the anode for LIBs in comparison with traditional carbon materials. However, the Li2FeSiO4 anode is subject to a fatal capacity degradation in long cycles, due to its low conductivity and serious particle agglomeration. With inspiration from the unique architecture based on the hybrid nanotubes consisting of active nanoparticles embedded in CNTs, a simple and efficient sol–gel method combined with subsequent calcination has been developed for the synthesis of porous Li2FeSiO4/C hybrid nanotubes. Benefiting from the intrinsic increased conductivity of the hybrid and its robust structure, as the anode for LIBs, it exhibits a high capacity (444.7 mA h g−1 at 0.2 A g−1), superior long cycling stability (161 mA h g−1 at 2 A g−1 after 3000 cycles) and an ultra-high rate capability (261.1 mA h g−1 at 1 A g−1 and 112.9 mA h g−1 at 8 A g−1). Surprisingly, the Na2FeSiO4/C hybrid nanotube also shows satisfactory application prospects as the anode for sodium ion batteries (SIBs). Such hybrids furnish attractive potential for high-performance LIB/SIB anodes, which would be a promising substitution for carbon anodes.