Modeling Stack Pressure Effects on Interfacial Void Growth in Solid-State Lithium Anodes
Maintaining 5 MPa stack pressure suppresses lithium void growth during high-rate stripping while active spring packs prevent separator fracture.
Contact Constriction
Meaning
Restricting electrical current flow through microscopic surface asperities generates localized interfacial resistance at mating conductor joints. Physical surfaces exhibit microscopic roughness that limits actual electrical contact to a small fraction of the apparent surface area. When current passes through these narrow touching points, contact constriction increases the effective path length and local current density.
High local resistance at these points produces localized Joule heating that degrades busbar joints over time.
Asperities Behavior
Microscopic surface peaks deform elastically and plastically under applied clamping force to form discrete conductive spots called a-spots. Increasing the mechanical clamping force enlarges individual contact spots and creates new conduction pathways across the joint interface. Higher applied pressure directly lowers electrical resistance by expanding total conductive surface area.
Surface hardness and yield strength govern how readily asperities flatten under compression.
Native Oxidation
Native oxide layers and organic contaminants create additional barriers to electron flow across microscopic contact points.
Thermal Runaway
Localized heating at micro-contacts increases metal resistivity, which concentrates heat production in a self-reinforcing loop. Unchecked temperature rise accelerates thermal oxidation of the surrounding conductor metal, further reducing effective contact area. In high-current battery systems, severe contact constriction leads to localized insulation melting and catastrophic joint failure.
Plating terminal surfaces with soft, oxidation-resistant metals such as silver or tin mitigates localized resistance spikes by maintaining stable electrical contact areas.