Exploring the electrochemical failure mechanism of lithium-ion batteries under salt spray condition

Abstract

As the global shipping industry transitions to low-carbon operations, electric ships emerge as a key alternative to traditional fuel-powered vessels, with the performance stability and safety of lithium-ion batteries (LIBs)—their core energy storage units—directly determining ship power system reliability. However, salt spray in marine environments poses a severe threat to the long-term service performance of LIBs. This study investigates lithium iron phosphate (LFP) batteries under simulated marine conditions via accelerated salt spray tests, utilizing multi-scale material characterization techniques to systematically reveal LIB degradation mechanisms. Incremental capacity analysis (ICA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) elucidates Cl⁻ penetration pathways in LFP electrodes and their differential impacts on microstructural integrity. The findings reveal that Cl⁻ penetration triggers complex internal reactions, causing electrode surface pitting, lattice contraction, and LiF interfacial layer formation, which lead to active material loss, lithium inventory depletion, and increased internal resistance. Furthermore, the evolution of key electrochemical parameters of an improved single particle model (SP+) confirm their correlation with salt spray-induced failure mechanisms and reveal multiple degradation pathways, including active material loss, interfacial reaction kinetic deterioration, and multi-stage ion transport limitations during liquid-phase diffusion.