Core-Shell Composite Cathode for Suppressing Micro Cracks

The patent applies local quality by creating a core-shell structure where the central core region contains lithium excess composition for high capacity, while the outer shell region has modified composition with doped elements that provide structural stability. This spatial differentiation of material properties allows the battery to achieve both high capacity from the core and extended lifespan from the protective shell that resists micro crack formation during cycling.

The patent employs composite materials by combining multiple metal oxides (such as Li1.2Mn0.54Co0.13Ni0.13O2) with doped elements (such as Ta2O5, Nb2O5, MoO3, or WO3) in specific ratios. This composite approach creates a material that integrates the high capacity characteristics of lithium excess materials with the structural stability provided by the doped elements, thereby simultaneously achieving high capacity and long cycle life without severe micro crack development.

The patent merges the doping process with the primary material synthesis by incorporating doped elements directly into the composite metal oxide structure during a single calcination process. Instead of separate doping steps, the doped elements are mixed with the base materials and processed together at high temperature to form the desired core-shell structure, thereby achieving complex microstructure control without proportionally increasing manufacturing complexity.

The patent utilizes parameter changes by optimizing the calcination temperature (700-800°C) and time (5-10 hours) to control the formation of the core-shell structure and the distribution of doped elements. By adjusting these processing parameters, the desired microstructure with suppressed micro cracks is achieved, allowing lifespan improvement through controlled material synthesis rather than complex post-processing steps.