Alkaline Earth Metal Passivation Layers for Uniform SEI Control

The patent applies preliminary action by forming the passivation layer on the alkaline earth metal electrode before immersing it into the electrolyte. The electrode is pre-treated with a passivation material (such as alkyl carbonates, carboxylic acid esters, or sulfones) to create a controlled, uniform layer that prevents direct contact between the electrolyte and metal surface. This pre-formed protective layer ensures homogeneous chemical composition and controlled morphology from the outset, eliminating the uncontrolled reduction and deposition that occurs with conventional in-situ SEI formation methods.

The patent applies composite materials by creating a layered structure consisting of the alkaline earth metal electrode combined with a passivation material layer. The composite structure integrates the high energy density advantage of alkaline earth metals (such as calcium or magnesium) with the protective properties of the passivation layer (alkyl carbonates, carboxylic acid esters, or sulfones). This composite electrode maintains the high capacity of the metal while the passivation layer provides corrosion resistance and stability, allowing the electrode to operate below the reduction potential of the solvent without direct degradation.

The patent applies parameter changes by carefully selecting passivation materials with specific molecular structures and properties that balance protection and conductivity. The passivation materials (alkyl carbonates, carboxylic acid esters, sulfones) are chosen based on their chemical composition, molecular weight, and functional groups to achieve optimal thickness and porosity. By adjusting these parameters, the passivation layer provides sufficient corrosion resistance while maintaining adequate ionic conductivity to support electrochemical reactions, allowing the electrode to function effectively at potentials below the solvent reduction potential.