Graphene activated 3D-hierarchical flower-like Li2FeSiO4 for high-performance lithium-ion batteries

Abstract

Development of a cathode material with safety, low cost, high energy and power densities, long life and excellent abuse tolerance for Li-ion batteries is critical for hybrid electric vehicles (HEVs) and electric vehicles (EVs). Here, we developed graphene activated 3D-hierarchical flower-like Li₂FeSiO₄ with secondary nanopetals (G@3D-HFLFS), which exhibited a discharge capacity of 327.2 mA h g⁻¹ (specific energy of 879 W h kg⁻¹) approaching the full theoretical capacity with large-current and long-life performance. The electrochemical reaction mechanism of G@3D-HFLFS was investigated by Mössbauer spectroscopy and parallel model X-band ESR. The high performance can be attributed to the secondary petal-like structures having an ultra-rapid Li-ion diffusion along the minimum length, the graphene coating layers facilitating double transport of electrons and Li-ions, and the special hierarchical structure with an optimal petal thickness possessing excellent structural stability. These results clearly demonstrate that our novel material is a promising cathode for commercial applications that require high energy and power densities, long operating life and excellent abuse tolerance.