The Y3+ and W6+ co-doping into Ni-rich Co‑free single-crystal cathode LiNi0.9Mn0.1O2 for achieving high electrochemical properties in lithium-ion batteries

Kinetic limitations and interfacial instability are critical issues hindering the commercial application of single-crystal Ni-rich Co-free cathodes. Herein, the strategy of Y/W co-doping has been performed to achieve high electrochemical performance of single crystal LiNi0.9Mn0.1O2 cathode. As a result, the Y3+ and W6+ co-doped sample presents an obvious promotion capacity retention of 82.1% at 1.0 C after 100 cycles, when compared to that of undoped sample (71.9%). Furthermore, even at 3.0 C, the co-doped sample displays a high specific capacity of 152.0 mAh g−1, while the value for the pristine is only 139.8 mAh g−1. XRD, TEM and XPS results clarify that the co-modification with Y3+ and W6+ cations can stabilize the crystal structure and reduce the Li+/Ni2+ mixing. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that Y3+ and W6+ co-doping can decrease potential polarization and electrochemical impedance, thereby effectively improve the diffusion kinetics of lithium ions. This study provides a promising route to prepare advanced Ni-rich Co-free single crystal cathode materials for lithium-ion batteries.