Nitride-Modified Metal Fluoride Electrodes for Conductivity

The patent applies composite materials by combining metal fluoride particles with carbon materials (graphite, amorphous carbon, carbon nanotubes, or graphene) to form a composite electrode structure. The carbon component provides electrical conductivity and structural stability, while the metal fluoride provides high capacity through conversion reactions. This composite approach resolves the contradiction by maintaining the high capacity benefit while mitigating the conductivity and reversibility problems through the carbon matrix.

The patent employs porous materials by creating a porous carbon matrix or porous metal fluoride structure that allows efficient ion transport and accommodates volume changes during conversion reactions. The porous structure provides short diffusion paths for lithium ions, maintains electrical contact, and accommodates the expansion/contraction of metal fluoride particles, thereby improving both conductivity and reversibility while preserving high capacity.

The carbon-metal fluoride composite structure maintains small separation distances between reaction products while ensuring continuous electrical contact through the conductive carbon matrix. The carbon phase acts as a percolating network that provides electrical pathways even when metal fluoride particles are finely divided, thus simultaneously achieving good reversibility and maintained conductivity throughout cycling.

The patent employs thin carbon coatings or shell structures around metal fluoride particles or as a continuous matrix. These thin carbon layers maintain intimate contact between reaction products, accommodate volume changes, and provide continuous electrical pathways. The flexible nature of the carbon shell allows it to adapt to the changing morphology of metal fluoride during cycling while maintaining both reversibility and electrical contact.