Core-Shell Metal Composite Hydroxide for Stable High-Capacity Cathodes

The patent applies local quality by creating a core-shell structure where the inner core region contains a lithium-nickel composite oxide with high nickel content (0.6 ≤ x < 0.8) for high capacity, while the outer shell region has a lower nickel content (0.3 ≤ x < 0.6) or contains manganese for thermal stability. This spatial differentiation of composition allows each region to optimize its function: the core provides capacity while the shell provides thermal stability and protects the core during charging/discharging cycles.

The patent changes the compositional parameters by using a gradient structure where the nickel content varies from the core to the shell (x decreases from core to shell). This parameter gradient allows the material to achieve high voltage characteristics (needed for energy density) while reducing overall cobalt content by replacing it with nickel in the core region and using protective shell structures, thereby lowering manufacturing costs while maintaining performance.

The patent applies preliminary action by forming the core-shell structure during the crystallization process itself rather than through subsequent complex post-processing steps. The method involves adding nickel salt and manganese salt at different stages: first forming the core with high nickel content, then adding more manganese salt to form the shell with lower nickel content. This integrated approach during synthesis simplifies manufacturing compared to separate coating or surface-modification processes.