Meaning
Electrodeposition growth inside a cell creates metallic needles that bridge the gap between opposing electrodes. Dendrite penetration occurs when these crystalline structures pierce the separator, causing an internal short circuit that initiates thermal runaway.
Growth Kinetics
Lithium ions migrate through the electrolyte toward the anode surface during charging. Irregular flux distribution promotes localized deposition, forcing metal to sprout outward in needle-like arrays. Repeated cycles accelerate the formation of these pathways, as microscopic cracks in the solid electrolyte interphase provide nucleation sites.
High current densities exacerbate the physical extension of the filaments toward the cathode.
Separator Resistance
Porous materials block physical contact while allowing ionic flow to maintain circuit connectivity. Performance limits depend on the mechanical strength and pore tortuosity of the membrane to divert potential growth. Thinning the layer improves energy density but invites risk as the material fails to stop the advancing metal.
Manufacturers monitor pressure and electrolyte additives to modify the growth morphology of the deposit.
Failure Mechanism
Direct electrical connectivity between electrodes triggers a localized discharge that releases stored energy as heat. Massive temperature spikes degrade adjacent components and ignite combustible electrolyte fluids. Severe internal shorts frequently lead to total device destruction and permanent capacity loss.
Safe operating zones require strict charge control to inhibit conditions that allow formation of these conductive bridges.
