Suppression and Mechanism of Voltage Decay in Sb-Doped Lithium-Rich Layered Oxide Cathode Materials

Voltage decay during cycling is the major problem for lithium-rich layered oxide cathodes. Here, we designed Sb-doped lithium-rich layered oxides prepared by a coprecipitation-solvent thermal method, aiming to alleviate the voltage decay of lithium-rich layered oxides. The midpoint discharge voltage and specific capacity of Li_1.20Ni_0.133Co_0.133Mn_0.633Sb_0.01O₂ (LLMO-Sb1) demonstrate almost no decaying after 100 cycles at 1 C. Moreover, it exhibits a large rate capacity (215 mAh g^-1 at 5 C). The suppressed voltage decay and enhanced cycle performance of Sb-doped material are attributed to the high Sb-O bond energy, which can enhance the stability of the layered structure and suppress the layered-to-spinel phase transition. Moreover, Sb doping improves the rate capacity by reducing the energy barrier of lithium ion diffusion. This work opens a gate to prevent the oxidation of superoxo and peroxo, stabilizing the layered structure by selecting an element with a suitable radius and electronegativity.