Al/Zr synergetic modification tailored low-cobalt single crystal LiNi0.72Co0.05Mn0.23O2 cathode for high-performance lithium-ion battery

N ickle (Ni)-rich layered oxides as promising candidate of high-capacity cathode materials have aroused extensive concern primarily regarding their higher specific capacity. However, the major hurdle of Ni-rich cathodes (Ni content ≥0.7) is their poor cycling stability, which often suffers from the release of oxygen, structural degradation and increased impedance during cycling, especially at high voltage or high temperature. Herein, we demonstrated a feasible solid phase method for easy industrialization based on the Al ³⁺/Zr ⁴⁺ co-doping in LiNi _0.72Co _0.05Mn _0.23O ₂ (A _XZ _Y-NCM) single-crystal cathode. The optimized A _0.5Z _0.5 -NCM single-crystal material exhibited greatly enhanced structural and thermal stability. XRD refinement results indicated that both Al ³⁺ and Zr ⁴⁺ were mainly located in transition metal (TM) sites, strengthening the layered structure through strong M-O bonds and inhibiting cation mixing. In-situ XRD revealed that the synergistic rivet effect of Al/Zr co-doping alleviates anisotropic lattice stress-strain during charge/discharge process. Accordingly, the A _0.5Z _0.5-NCM cathode can output a high initial capacity of 177.3 mAh g ⁻¹ at 1 C, and captured a more desirable capacity retention of 85.10 % than that of U-NCM (74.33 %) at 1 C over 200 cycles. Even at a high voltage of 4.5 V, its capacity retention can still reach 82.37 %, significantly surpassing the unmodified U-NCM (31.0 %). The above results demonstrated that well-designed dual doping is highly effective for strengthen structure stability and cycling performance of Ni-rich cathodes.