Stable V-doped LiMnPO4/C cathode material for Li-ion batteries produced by a fast and facile microwave-assisted synthesis

Abstract

Inexpensive, stable, and environmentally benign cathode materials with high energy density for Li-ion batteries have been the focus of extensive research in previous years. For this, LiMnPO4 has been proposed as cathode material due to their relatively high energy density compared to its iron-base counterpart, LiFePO4. However, low Li-ion conductivities precludes LiMnPO4 to reach its full performance targets as cathode material. In this research, we present a fast microwave-assisted route to obtain nanoparticles and subsequently a carbon coated olivine-type material: LiMnPO4/C. This route was modified to study the effect of vanadium on its performance as cathode for Li-ion batteries. For this, different conditions for the synthesis were investigated. The optimised method consisted of dissolving the precursors in a solution comprised of triethylene-glycol and water followed by microwave heating at 180∘C for only 10 min. Doping with 2.5–5% V increased the stability of LiMnPO4 (91.3% retention after 50 cycles vs 74.4% without doping), along with the Li-ion diffusivity, C-rate capabilities and specific capacities up to 146.7 mA h g−1. The results presented in here prove that a stable V-doped LiMnPO4 can be produced by a fast and facile microwave-assisted synthesis to be used as cathode material for Li-ion batteries.