Pre-Lithiated Oxide Coating for Silicon Anode Volume Expansion

The patent employs a multi-layer nested structure where the silicon-based negative electrode particle is sequentially coated with conductive carbon material and then pre-lithiated metal oxide. This nested configuration allows the silicon core to maintain its high capacity function while being progressively protected by outer layers that constrain volume expansion and stabilize the structure during lithium ion insertion and extraction cycles.

The patent creates a composite material system combining silicon-based materials with conductive carbon and pre-lithiated metal oxide. This composite structure integrates the high capacity advantage of silicon with the structural stability and protective properties of the coating materials, achieving both high theoretical capacity and resistance to volume expansion through material composition rather than relying on a single material's properties.

The patent applies pre-lithiated metal oxide as the outermost coating layer, which has been预先 treated with lithium. This preliminary lithium incorporation allows the SEI to form more stably during initial charging cycles, preventing the unstable SEI formation and subsequent lithium ion consumption that occurs with plain silicon oxide. The pre-lithiation compensates for initial lithium loss and promotes reliable SEI development.

The pre-lithiated metal oxide acts as an intermediary layer between the silicon oxide core and the electrolyte. This intermediate coating mediates the interaction between the electrode material and electrolyte, facilitating stable SEI formation while preventing direct contact that would cause unstable SEI and lithium ion consumption. The intermediary layer controls the interface chemistry to achieve reliable electrochemical performance.

The patent changes the chemical composition parameter of the outermost coating layer by using pre-lithiated metal oxide instead of conventional non-lithiated coatings. This parameter change (incorporating lithium in the coating) directly addresses both volume expansion and SEI stability issues, leading to improved capacity retention. The compositional modification of the coating layer enables simultaneous resolution of multiple degradation mechanisms.

The patent segments the protective function into multiple specialized layers: an inner conductive carbon layer for electrical conductivity and initial structural support, and an outer pre-lithiated metal oxide layer for SEI stabilization and volume expansion control. This segmentation of functions across layers allows each layer to optimize its specific role, achieving comprehensive protection against capacity fading that single-layer coatings cannot provide.