Co‐Doping of Al³⁺ and Ti⁴⁺ and Electrochemical Properties of LiNiO₂ Cathode Materials for Lithium‐Ion Batteries

Abstract

LiNiO2 cathode material for lithium‐ion batteries has the advantages of high specific capacity, abundant resources, and low cost, but it suffers from difficulties in preparation, structural instability, and serious capacity decay. In this work, highly pure and layered structural LiNi0.95AlaTi0.05‐aO2 (a=0, 0.025, 0.05) cathode materials were synthesized by a simply sol‐gel method. The cation mixing of Ni2+ and Li+, structural deterioration, irreversible conversion between H2 and H3 phases and unstable surface and CEI (Cathode‐electrolyte interface) film can be effectively suppressed by co‐doping with Al3+ and Ti4+. A preferred LiNi0.95Al0.025Ti0.025O2 sample provides a discharge specific capacity of 223 mAh g−1 at 0.1 C and 148.32 mAh g−1 at 5 C, a capacity retention of 72.7 % after 300 cycles at 1 C and a Li+ diffusion coefficient of about 2.0×10−9 cm2 s−1.