The Cu-Y co-doping LiNi0.5Mn1.5O4 with modified morphology and enhanced electrochemical property for a 5 V lithium-ion battery

LiNi0.5-xCuxMn1.48Y0.02O4 (x = 0.02, 0.03, 0.04) and LiNi0.5Mn1.5O4 (LNMO) samples were prepared successfully via the sol-gel method. The lattice parameter and the degree of Ni/Mn disorder for LNMO samples were increased by doping Cu2+ and Y3+ ions, which is benefit for improving lithium-ion diffusion rate. The Cu-Y co-doped samples possessed truncated octahedral morphologies with (111) facet and exposed (100) facet by modified the co-doped Cu-Y content. The (100) facet helped to accelerate the Li+ ion diffusion while the (111) facet inhibited the dissolution of transition metals at the solid interface. The LiNi0.47Cu0.03Mn1.48Y0.02O4 (0.03 Cu-Y) sample exhibited high initial discharge specific capacity of 145.7 mAh g(-1) which was far higher than that of pristine sample (113.8 mAh g(-1)). After 100 cycles at 1 C, the 0.03 Cu-Y sample retained discharge specific capacity of 137.2 mAh g(-1) with superior retention of 96.79% while the undoped sample only retained 108.8 mAh g(-1) and the retention is 95.79% at the same condition. The improved electrochemical property of the Cu-Y co-doped sample maybe attribute to the stable structure that decrease Ohmic polarization and the suitable morphology that is conducive to accelerate the Li+ ion diffusion.