Silicon Compound Negative Electrode Active Material Surface Stabilization

The patent uses a composite material consisting of silicon compound particles (SiOx where 0.5 ≤ x ≤ 1.6) containing lithium and polyphenylene compound components. This composite structure combines the high capacity advantage of silicon with the surface stability provided by the polyphenylene compound, resolving the contradiction between capacity improvement and cycle characteristic deterioration.

The patent applies local quality by introducing polyphenylene compound components specifically to the surface region of the silicon compound particles. This creates a differentiated structure where the core silicon compound provides high capacity while the surface polyphenylene layer provides stability and prevents electrolyte decomposition, thus improving cycle characteristics without sacrificing capacity.

The patent applies preliminary action by pre-forming a stable surface layer of polyphenylene compound on the silicon compound particles before they come into contact with the electrolyte. This pre-established protective layer prevents surface breakdown during initial charging cycles, avoiding the generation of new surfaces that would trigger electrolyte decomposition and consumption.

The patent converts the potentially harmful effect of surface breakdown into a benefit by using the polyphenylene compound to create a controlled, stable surface structure. Instead of uncontrolled surface fracture leading to electrolyte decomposition, the polyphenylene layer provides a stable interface that maintains reaction area while preventing harmful electrolyte consumption.