A nano-truncated Ni/La doped manganese spinel material for high rate performance and long cycle life lithium-ion batteries

Abstract

The spinel LiMn₂O₄ cathode material provides high energy and low cost, but suffers from poor cycling performance and rate capability owing to Mn dissolution and Jahn–Teller distortion. Herein, our design concept is to combine Ni–La co-doping with the nanoscale truncated octahedron to solve this issue; namely, a novel nano-LiNi_0.08La_0.01Mn_1.91O₄ cathode material with a truncated octahedron is fabricated for the first time through a facile and quick solution combustion approach. It is found that the Ni–La dual doping promotes the {111} surface growth in spinel LiMn₂O₄, which endows the nano-LiNi_0.08La_0.01Mn_1.91O₄ sample with the majority of {111} facets for minimal Mn dissolution and a few truncated {100} facets for rapid Li⁺ ion migration channels, as well as the nanoscale particles facilitating decreased electronic and ionic diffusion paths. In addition, the introduction of Ni–La elements can strengthen the crystal structure stability and restrain the Jahn–Teller effect effectively. Consequently, the nano-LiNi_0.08La_0.01Mn_1.91O₄ presents excellent electrochemical properties with high first discharge capacities of 114.9 and 100.4 mA h g⁻¹ at 1C and 5C, respectively. Importantly, at the current rate up to 10C, a capacity retention ratio of 89.0% is acquired after an ultra-long 1000 cycles. The CV and EIS measures manifest that the Ni–La dual doping improves the Li⁺ ion transport rate and weakens the reaction barrier in the nano-LiNi_0.08La_0.01Mn_1.91O₄. This research will be a promising candidate for developing long cycle power lithium-ion batteries.