Lithium-Ion Cathode Sulfate Coating for Stable Electrolyte Interface

The patent changes the concentration parameter of sulfate ions from the conventional ≥0.4% to a lower range of 0.01-0.3%, which fundamentally alters the composition control requirements while maintaining the capacity improvement effect. This parameter change resolves the contradiction by achieving the same reliability improvement with reduced compositional complexity.

The patent applies local quality by introducing sulfate ions specifically at the surface or interface regions of the cathode material rather than uniform bulk doping. This localized approach achieves the necessary modification effect with minimal overall sulfate content, resolving the contradiction between capacity improvement and composition control complexity.

The patent extracts and eliminates the liquid phase precipitation step from the manufacturing process. Instead of using complex wet chemistry methods involving liquid phase precipitation and organic solvent rinsing, the invention employs a simplified solid-state or vapor-phase approach that achieves the same coating effect without the complicated process steps, thereby improving ease of manufacture while maintaining coating reliability.

The patent replaces the chemical precipitation mechanism (liquid phase reaction) with an alternative mechanism such as solid-state reaction or vapor deposition. This substitution eliminates the need for liquid phase processing and subsequent solvent removal steps, significantly simplifying the manufacturing process while achieving equivalent or superior coating effects.

The patent introduces an intermediary substance that facilitates the reaction between sulfate and residual lithium. Instead of directly using lithium sulfate which cannot react further, the invention employs a different sulfate compound that acts as an intermediary to generate lithium sulfate in situ, which then performs the desired function. This intermediary approach resolves the contradiction by enabling the reaction pathway while maintaining sulfate selection flexibility.

The patent applies preliminary action by first introducing a sulfate compound that reacts with residual lithium during a pre-treatment or initial processing stage. This preliminary reaction converts the residual lithium into lithium sulfate, which then remains in the structure to provide the desired capacity improvement. This sequential approach resolves the contradiction by performing the necessary chemical transformation before final structure formation.