Towards Ni-rich layered oxides cathodes with low Li/Ni intermixing by mild molten-salt ion exchange for lithium-ion batteries

In the conventional synthesis of layered transition metal oxides, the high-temperature process not only causes lithium loss due to evaporation, but also facilitate the inevitable cation mixing of Li + and Ni 2+ , resulting in severe shifts in their stoichiometric ratios and thus structure instability. Herein, we report a universal ion-exchange method to prepare Ni-rich layered oxide materials LiNi 0.85 Co 0.06 Mn 0.09 O 2 (NCM85) with low Li/Ni intermixing at a low reaction temperature of 300 °C, where sodium-based layered oxides (NaNi 0.85 Co 0.06 Mn 0.09 O 2 ) were used as precursors for ion exchange with Li + ion in lithium molten salts. By studying the effects of ion-exchange time and additional heat treatment on the structure and performance of the layered oxide materials, we established the processing-structure-performance relationships for Ni-rich NCM85 materials. Moreover, we further demonstrated the universality of this ion-exchange method and processing-structure-performance relationships for other layered oxide materials including LiNi 0. 5 Co 0.2 Mn 0.3 O 2 and LiNi 0.5 Mn 0.5 O 2 . We anticipate that such universal method of ion exchange and universal processing-structure-performance relationships can guide the rational design and synthesis of other layered oxide materials for lithium-ion batteries. The Ni-rich layered oxides cathodes with low Li/Ni intermixing obtained by ion exchange at a low reaction temperature, where sodium-based layered oxides were used as precursors for ion exchange with Li + ion in lithium molten salts. • The materials prepared by ion exchange solve theproblems of Li/Ni mixing and high temperature sensitivity. • The relationship between processing-structure-performance is constructed by studying the ion exchanged materials. • The universality of ion exchange and processing-structure-performance relationships for other materialsis demonstrated.