SEI Layer Growth & Battery Capacity Fade

Every lithium-ion battery ages even when no one is using it, because a thin passivation layer — the solid-electrolyte interphase (SEI) — keeps growing on the anode surface, one diffusion-limited layer at a time. This simulator renders a graphite anode particle in 3D, grows a physically-scaled SEI shell around it using the standard parabolic (√t) growth law with Arrhenius temperature dependence, and animates the cyclable lithium-ion population as it is progressively trapped into the film. Temperature, cycling rate and an electrolyte-additive toggle all feed the real rate equations, with live readouts for SEI thickness, capacity retention and relative cell impedance — the same three numbers battery engineers track to predict calendar life and cycle life.