Single-Crystal Ternary Cathode With Gradient Doping for High-Voltage Cycling

The patent applies local quality by implementing gradient doping where the doping element concentration varies spatially - higher concentration at the surface for stability and lower concentration in the interior for capacity. This is achieved through controlled doping processes that create a concentration gradient from the particle surface inward, allowing simultaneous optimization of structural stability and electrochemical capacity.

The patent utilizes parameter changes by systematically varying the doping element concentration, particle size, and crystal structure parameters to achieve optimal performance. Specifically, the doping content is controlled within a specific range (0.01-0.1 mol ratio) and particle size is optimized (3-8 μm) to balance stability and capacity, demonstrating parameter optimization to resolve the contradiction.

The patent employs thin film coating layers (5-20 nm thickness) of metal oxides such as Al2O3, TiO2, or Li2SiO3 on the cathode material surface. These thin protective films provide sufficient barrier function to reduce surface side reactions and improve cycling stability while maintaining adequate lithium ion diffusion kinetics, thus resolving the contradiction between protection and conductivity.

The patent creates composite structures combining the ternary cathode material with coating layers of different functional materials. The composite structure integrates the high-capacity ternary material core with the protective and conductive coating shell, achieving synergistic effects that simultaneously improve cycling performance and maintain low diffusion resistance through proper material selection and interface engineering.

The patent applies segmentation by dividing the cathode material into uniformly sized particles with controlled diameter (3-8 μm) and spherical morphology. This segmentation approach increases the number of particles while maintaining optimal size for both reduced surface reaction area and sufficient ion diffusion paths, resolving the contradiction between minimizing surface reactions and maintaining fast ion transmission.

The patent utilizes dimensional optimization by controlling particle size within a specific range and creating spherical morphology with uniform size distribution. This dimensional control ensures that particles are large enough to reduce specific surface area and contact reactions, yet small enough to maintain short lithium ion diffusion paths, achieving optimal balance through precise dimensional parameter selection.