Improving the fast discharge performance of high-voltage LiNi0.5Mn1.5O4 spinel by Cu2+, Al3+, Ti4+ tri-doping

•Cu, Al, Ti Tri-doping improves electronic conductivity of LiNi0.5Mn1.5O4.•Cu, Al, Ti Tri-doping peculiarly enhances the Li+ diffusion coefficient at ∼4.7 V.•Cu, Al, Ti Tri-doping significantly improves the rate capability of LiNi0.5Mn1.5O4.

The sluggish Li+ ion diffusion coefficient at ∼4.7 V (vs. Li+/Li) greatly impairs the fast discharge performance of LiMn1.5Ni0.5O4 cathode material. Herein, a tri-doping strategy is proposed where Cu2+, Al3+, Ti4+ ions are partially substituted for Ni2+ and Mn4+. Cu2+, Al3+, Ti4+ tri-doping effectively suppresses the LixNi1−xO impurity phase, increases the cation mixing in the octahedral B-site in the spinel, enlarges the electronic conductivity, and enhances the structural stability. Most importantly, the Li+ diffusion coefficients show a peculiar boost at 4.7 V by two orders of magnitude after tri-doping. Compared to the pristine LiMn1.5Ni0.5O4 (denoted P-LNM), the tri-doped Li[Ni0.455Cu0.03Al0.03Mn1.455Ti0.03]O4 (denoted TD-LNM) exhibits much better fast discharge performance, delivering a specific capacity of ∼101 mAh g−1 at 100 C discharge rate.

Graphical abstractFor the LiMn1.5Ni0.5O4 cathode material, the sluggish Li+ ion diffusion coefficient around the ∼4.7 V (vs. Li+/Li) plateau greatly impair its fast discharge performance, which therefore limit its application in electric vehicles. Herein, a tri-doping strategy is proposed where Cu2+, Al3+, Ti4+ ions are partially substituted for Ni2+ and Mn4+. After tri-doping, the Li+ diffusion coefficient at 4.7 V (vs. Li+/Li) is boosted by two orders of magnitude. Compared to the pristine LiMn1.5Ni0.5O4 (denoted P-LNM), the tri-doped Li[Ni0.455Cu0.03Al0.03Mn1.455Ti0.03]O4 (denoted TD-LNM) exhibits much better fast discharge performance, delivering a capacity of ∼101 mAh·g−1 at 100 C discharge rate.Figure optionsDownload full-size imageDownload as PowerPoint slide