Suppressing Cycling-Induced Volume Expansion in Li2FeSiO4 Carbon Nanofibers via Electrospinning toward Symmetric Lithium-Ion Batteries.

Li2FeSiO4 is a promising lithium-ion battery (LIB) material with high capacity, low cost, and exceptional stability. However, the commercial viability of Li2FeSiO4 is hindered by poor electronic conductivity, sluggish Li+ diffusion, and challenges caused by significant volume changes. In this work, Li2FeSiO4 particles are embedded in reduced graphene oxide (rGO)/carbon nanofibers (CNFs) by a simple and scalable electrospinning method. Benefiting from ultrafine Li2FeSiO4 nanoparticles embedded in 1D CNFs, Li+ diffusion paths are effectively shortened. Meanwhile, the incorporated rGO facilitates the uniform nucleation and dispersion of particles in CNFs, thus effectively suppressing the volume expansion associated with the Fe0/Fe2+ redox reaction. Consequently, the multi-electron redox capability of Fe0/Fe2+/Fe3+/Fe4+ is fully utilized, allowing Li2FeSiO4 to function as both a cathode and an anode in a symmetrical full cell. As expected, the optimal sample delivered an initial discharge capacity of 164.2 mAh g-1 at 0.1 A g-1 as a cathode, retaining 92.6 mAh g-1 at 1.6 A g-1. As an anode, the electrode exhibited a high reversible capacity of 760.4 mAh g-1 at 0.5 A g-1. Moreover, the symmetric full cell (LFS/C/10GO∥LFS/C/10GO) achieved a reversible capacity of 110.7 mAh g-1 at 0.1 A g-1. This work reports a simple, scalable synthesis of uniform nano-Li2FeSiO4 for advanced symmetric LIBs.