Meaning
Mechanical bonding strength between the active electrode slurry and the metal foil substrate determines the structural integrity and electrical continuity of a battery electrode. High current collector adhesion ensures that the active material layer remains securely attached to either the aluminum or copper foil during battery manufacturing and subsequent cycling. This property is evaluated during the design phase to minimize the risk of internal resistivity increases.
Manufacturing Influence
Application of slurry onto the metal foil must be followed by precise drying and calenders to establish a durable bond. During the drying phase, binder migration can occur, moving the polymer away from the current collector surface and weakening the bond. To maximize current collector adhesion, the slurry composition, solvent evaporation rate and compression force must be carefully balanced.
Failure Mechanism
Stress concentrations generated during cell operation cause the active material to pull away from the metallic substrate. When the bond fails, a physical gap forms between the active material and the metal foil, stopping the flow of electrons. Poor current collector adhesion leading to this type of mechanical detachment results in localized hot spots and rapid capacity degradation.
Cell Longevity
Maintenance of this bond across many hundreds of cycles is critical to preventing sudden cell failure. Slurry formulations are rejected if they cannot sustain the necessary bonding force after exposure to liquid electrolyte.
