Bulk doping of tungsten improves the structure stability and electrochemical performance of layered Ni-rich material

Abstract

Tungsten doping has attracted great attention to improve the electrochemical performance of layered Ni-rich cathodes. However, the role of tungsten dopant remains unclear since tungsten is usually rich on surface rather than incorporated into bulk lattices in layered Ni-rich particles, therefore the improved performance is mostly ascribed to the W coating layers or preferred orientation microstructures. In this work, as low as 0.1 mol% of tungsten bulk doping is introduced into a layered Ni-rich material during the coprecipitation of precursor. As a result, the tungsten bulk-doped LiNi0.8Co0.1Mn0.1O2 (NCM811-W) cathode shows significantly improved cycling stability at 1 C, with a capacity retention of 95.06 % after 200 cycles (compared to 70.83 % for the undoped NCM811 cathode). The improved performance of NCM811-W cathode is mainly attributed to strong W–O bonding within the lattices of NCM811, which can increase the reversibility of the two-phase reaction (H2–H3) of layered Ni-rich material and reduce the migration energy barrier of lithium ions. This work represents a step forward in understanding the high-valence metal ions-doping for high-performance Ni-rich cathodes.