Hierarchical porous Li2FeSiO4/C composite with 2 Li storage capacity and long cycle stability for advanced Li-ion batteries

Abstract

A hierarchical porous Li₂FeSiO₄/C composite was prepared using an in situ template synthesis by tetraconstituent co-assembly of resols, nitrates, silica oligomers, and a triblock copolymer surfactant. The structural and electrochemical characterizations revealed that the Li₂FeSiO₄/C composite has a hierarchical micro-, meso- and macro-porous structure, in which macrosized pores provide abundant electrolyte channels for fast ionic transport, while the microporous network offers large accessible electrochemically active areas for the Li insertion reaction. The Li₂FeSiO₄/C composite demonstrates a very high capacity of 254 mA h g⁻¹ at room temperature with excellent cycling stability and rate capability, corresponding to 77.5% utilization of its theoretical 2 Li storage capacity. The results from this study suggest a feasible approach to improve dramatically the electrochemical utilization and cyclability of the kinetically sluggish intercalation compounds by creating an electrochemically favorable porous structure and the synthetic strategy described in this work may be extended to fabricate other types of porous multifunctional materials for energy storage, catalysis and other applications.