A new concentration gradient design employing wet-doped tungsten for advanced Ni-rich cathodes

Abstract

To overcome the intrinsic challenges associated with Ni-rich cathodes, heteroelement doping has been widely explored for the fabrication of concentration-gradient cathodes. However, the majority of studies have adopted conventional dry doping processes during cathode calcination, leading to non-uniform dopant distributions and structural heterogeneity, which ultimately compromise any improvements in the cycling performance. In this study, a new compositionally partitioned design is proposed, which comprises a NiMn core and a NiCoW shell, along with a regionally targeted wet doping strategy. A spherical precursor with a composition of [Ni0.900Co0.075Mn0.020W0.005](OH)2, consisting of a [Ni0.960Mn0.040](OH)2 core and a uniform [Ni0.820Co0.170W0.010](OH)2 shell, was successfully synthesized via a co-precipitation approach. The proposed targeted wet doping strategy selectively concentrated tungsten in the shell region, where structural or interfacial degradation was the most severe, thereby maximizing the performance improvement in the cathode material. The modified crystal structure and well-regulated primary particle morphology contributed to the enhanced cycling stability of the concentration-gradient Ni-rich cathode and significantly reduced heat generation during electrochemical cycling. Therefore, this regionally targeted W doping strategy provides a practical and scalable approach for developing next-generation Ni-rich cathode materials for lithium-ion batteries with enhanced cycle life and improved thermal stability.