Preparation of nanorod-assembled CNT-embedded LiMnPO4 hollow microspheres for enhanced electrochemical performance of lithium-ion batteries

Abstract

LiMnPO₄ is a promising cathode material for lithium-ion batteries, but it has drawbacks of poor electronic conductivity and low Li⁺ diffusivity. Here, we have attempted to simultaneously improve electron transfer and Li⁺ migration by preparing LiMnPO₄/CNTs hollow microspheres. These LiMnPO₄/CNTs hollow microspheres are synthesized using precipitated Li₃PO₄/CNTs hollow microspheres as a sacrificial template and a subsequent solvothermal reaction. In these LiMnPO₄/CNTs hollow microspheres assembled using radial-aligned (010)-exposed nanorods, the embedded CNTs form connecting electronic conductive network and the aligned pores form straight Li⁺ diffusion channels. Due to these synergistic effects, the LiMnPO₄/CNTs hollow microspheres present superior electrochemical performance. The capacities of the LiMnPO₄/CNTs hollow microspheres only decrease from 166 to 116 mA h g⁻¹ as the rate increases from 0.05 to 5 C. Even when cycled at a rate of 1 C, the LiMnPO₄/CNTs hollow microspheres achieve a discharge capacity of 134 mAh g⁻¹ with about 96% capacity retention after 100 cycles. The excellent electrochemical performance can be ascribed to their CNT-embedded pore-aligned structure.