Strategic Integration of Cobalt-Free Layered–Spinel Cathodes via Solution Combustion Method for High-Performance Lithium-Ion Batteries

Structurally integrated cobalt-free layered-spinel cathode material with the composition Li_1.2Ni_0.24Mn_0.56O₂ (LNMO) was synthesized via the sucrose-assisted solution combustion method (SCM). The material was calcined at 650, 750, 850, and 950 °C, denoted as LNMO-650, LNMO-750, LNMO-850, and LNMO-950. Among these, the sample calcined at 850 °C exhibited excellent electrochemical performance due to the optimal phase composition achieved at this temperature. The synthesized LNMO materials are composed of both Li-rich layered (space group <i>C</i>2/<i>m</i>) and spinel phases (space group <i>Fd</i>3̅<i>m</i>) as evidenced by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and cyclic voltammetry (<i>CV</i>) analyses. LNMO-850 delivers a maximum specific capacity of 283 mAh g^-1 with an energy density of 952 Wh kg^-1 at 20 mA g^-1. At a higher current density of 200 mA g^-1, it retains 138 mAh g^-1 with 97% Coulombic efficiency and an energy density of 456.4 Wh kg^-1 in the 100th cycle. In addition, the LNMO-850 exhibits superior performance over temperatures ranging from 0 to 50 °C. Postcycling studies, such as ex-situ XRD, Raman, and HRSEM analysis, were carried out to evaluate the material's structural stability and morphological robustness after prolonged cycling.