Structural stabilization effect of Mg-Al co-doping on high-nickel layered cathode material LiNi0.9Co0.1O2

High-nickel layered oxide LiNi 0.9 Co 0.1 O 2 is a promising cathode material for lithium-ion batteries due to its high specific capacity and low cost. However, the internal stress generated during deep delithiation can cause microcracks, giving rise to rapid capacity decay and deteriorated thermal stability. In this work, Mg and Al ions are incorporated into the bulk phase of LiNi 0.9 Co 0.1 O 2 via high-temperature solid-state reaction. We demonstrate that Al 3+ doping enhances charge transfer between transition metal (TM) and oxygen layers, strengthening TM-O bonds and stabilizing the structure, thereby alleviating structural distortions under deep delithiation. More impressively, Mg 2+ doping significantly improves structural stability through a pillaring effect, effectively suppressing irreversible phase transitions during charge-discharge cycling. Consequently, Mg-Al co-doping optimizes the overall structural integrity of the high-nickel cathode, enhances its stability, and inhibits lattice oxygen release during long-term cycling. The Mg-Al co-doped LiNi 0.9 Co 0.1 O 2 delivers a remarkable capacity of 177.3 mAh g −1 after 100 cycles with capacity retention of 93.5 %, demonstrating outstanding cyclability. This Mg-Al co-doping strategy provides a simple and practical approach to enhance the electrochemical performance of high-nickel layered cathode materials.