One-pot synthesis of 3D hierarchical porous Li3V2(PO4)3/C nanocomposites for high-rate and long-life lithium ion batteries

Abstract

Li₃V₂(PO₄)₃ (abbreviated as LVP) is considered as a prospective cathode material for next-generation Li ion batteries due to its high specific capacity and high operating potential. However, its low electronic conductivity and the difficulty in morphology control restrict its widespread application. Carbon coating has been proved to be an effective method for solving these problems. However, too thick a carbon layer will act as a barrier for Li⁺ diffusion. 3D hierarchical porous materials with unique electronic and structural properties have exhibited outstanding advantages. However, most methods employed for fabricating the hierarchical porous materials need templates and need acid or alkali to remove the template afterwards. This is detrimental to the LVP material because the LVP reacts with both acid and alkali. Here we present a rational design for a hierarchical porous LVP/C nanocomposite via a one-pot process, in which F127 molecules and the LVP colloids induce self-assembly. After high-temperature annealing, the mesoporous structure was developed due to the decomposition of the F127 and then the LVP/C clusters piled up to form stacked macropores. As a cathode for Li ion batteries, the LVP/C nanocomposite exhibited excellent cycle stability (96% capacity retention over 800 cycles) and enhanced high-rate performance (117 mA h g⁻¹ at 20C). This method provides a new approach for synthesizing high-performance 3D hierarchical porous cathode materials used in other energy storage applications.