Achieving Enhanced Electrochemical Performance for Cobalt-Free Layered Cathode Material by Aluminum Doping

We introduce a facile strategy to greatly improve the electrochemical reversibility of cobalt-free cathode material by doping trace quantity of aluminum (Al) in LiNi0.65Mn0.35O2. X-ray diffraction and X-ray photoelectron spectroscopy results reveal that Al doping reduces the cation disorder consequently and hence increases structural stability. Electrochemical measurements show that rate capability and cycling stability are remarkably enhanced by Al doping. Al-doped LiNi0.65Mn0.35O2 exhibits the optimized electrochemical performance with a capacity retention of 94.2% after 200 cycles at 2 C in voltage range of 2.75-4.2 V in cylindrical full cell, demonstrating that Al-doped cathode exhibits enhanced cyclability, reduced polarization and high-rate capability during charge/discharge process. Moreover, the full cell shows good low-temperature performance with more than 70% capacity retention at -20 degrees C. The improved performances can be ascribed to the enhanced stability in layered structure of the Co-free material by the support of doped Al ions.