Synergistic effects of various morphologies and Al doping of spinel LiMn₂O₄ nanostructures on the electrochemical performance of lithium-rechargeable batteries

Nanostructured electrodes have recently received great attention as components in lithium rechargeable batteries, especially because of the high power produced by the fast kinetic properties of these unique structures. Here, we report the successful synthesis of various nanostructured morphologies of spinel lithium manganese oxide electrodes (nanorod, nanothorn sphere, and sphere) from a similarly shaped manganese dioxide precursor that was controlled with different aluminium contents by the hydrothermal method. Among these structures, nanothorn sphere structured LiAl_0.02Mn_1.98O₄ produces the highest discharge capacity of 129.8 mA h g^-1, excellent rate capability (94.6 mA h g^-1 at 20 C, 72% of 0.2 C-rate discharge capacity) and stable cyclic retention for 50 cycles. The excellent kinetic properties of the nanothorn sphere structure are not only due to the nanothorn sphere electrode having high surface area but also because the critical amount of Al in the nanothorn sphere electrode was located at the Mn site (16d) instead of the Li site (8a).