Synthesis of a Co–Ni doped LiMn2O4 spinel cathode material for high-power Li-ion batteries by a sol–gel mediated solid-state route

Abstract

A Co–Ni doped LiMn2O4 spinel cathode material with a nominal stoichiometry of LiMn1.95Co0.025Ni0.025O4 was synthesized by a sol–gel mediated solid-state route at a low temperature of 650°C, using a highly dispersed ultra-fine Mn3O4 as the Mn source. Also, a pelletizing process was adopted to optimize its morphology. It was revealed that the Co–Ni doped LiMn2O4 obtained consisted of porous nanoparticles-constructed LiMn1.95Co0.025Ni0.025O4 granules with a size of 30–50μm, which combined the favorable characteristics of both nano-sized and bulk materials, i.e. considerably large specific surface area and high tap density. The cathode material exhibited excellent electrochemical performance. Notably, its rate capability was extraordinarily high, which was superior to that of pristine or doped LiMn2O4 materials ever reported. It showed a discharge capacity of 119mAhg−1 at a current rate of 0.2C (1C=148mAg−1), and retained a capacity of 111mAhg−1 at 10C, presenting a 93% capacity retention. After 200 cycles at 1C and 25°C, it delivered a capacity of 112mAhg−1, retaining 97% of its initial capacity. After 100 cycles at 1C and 55°C, it showed a capacity of 110mAhg−1, preserving 96% of its initial capacity. The excellent electrochemical performance together with the facile synthesis process allowed the synthesized LiMn1.95Co0.025Ni0.025O4 to be a promising cathode material for high-power Li-ion batteries.