High-Rate Capability of LiNi0.9Mn0.1−xAlxO2 (NMA) (x = 0.01, 0.03, 0.05) as Cathode for Lithium-Ion Batteries

LiNi0.9Mn0.1−xAlxO2 (NMA) (x = 0.01, 0.03, 0.05) cathodes were synthesized via the co-precipitation method and continued with the calcination process in a tube furnace at 750 °C under flowing oxygen gas for 12 h. X-ray diffraction (XRD) revealed a well-formed and high-purity phase with a hexagonal structure. LiNi0.9Mn0.07Al0.03O2 (NMA 973) had the best electrochemical performance with the lowest redox peak separation, the smallest charge transfer resistance (71.58 Ω cm−2), the highest initial specific discharge capacity of 172 mAh g−1 at 0.1C, and a capacity retention of 98% after 100 cycles. Under high current density at 1 C, NMA 973 had excellent specific discharge capacity compared to the other samples. The optimal content of Mn and Al elements is a crucial factor to obtain the best electrochemical performance of NMA. Therefore, NMA 973 is a promising candidate as a cathode for high-energy-density lithium-ion batteries.