Silicon Anode Coating Structure for Volume Expansion Buffering

The patent employs a multi-layer nested coating structure where an inner carbon coating layer encapsulates the silicon-based core, and an outer phenyl-compound coating layer covers the carbon layer. This nested configuration allows the silicon core to expand and contract during lithium insertion/extraction while the concentric coating layers provide progressive mechanical support and buffer the volume changes, preventing structural degradation and maintaining integrity throughout cycling.

The patent utilizes a composite material system combining silicon-based active material with carbon matrix and phenyl-compound polymer coating. The carbon layer provides mechanical strength and electrical conductivity, while the phenyl-compound layer offers flexibility and adaptability to volume changes. This composite structure synergistically combines the high capacity of silicon with the structural stability of carbon and polymer materials.

The patent pre-coats the silicon-based core with carbon and phenyl-compound layers before battery assembly. These pre-formed protective layers serve as artificial passivation layers that prevent direct contact between the silicon surface and electrolyte, eliminating the need for extensive electrolyte consumption during initial SEI formation. The phenyl-compound layer specifically is designed to be stable and prevent further unwanted reactions.

The carbon layer and phenyl-compound layer act as intermediary barrier layers between the silicon-based active material and the electrolyte. These intermediary layers provide the necessary protection and passivation function while being more stable and less consumptive than the natural SEI layer that would form on bare silicon, thereby reducing electrolyte and lithium ion consumption.