Meaning
Irreversible electrochemical and structural changes alter active materials, reduce energy capacity, increase gas generation, and elevate internal resistance over time. Parasitic chemical reactions drive lithium ion degradation during both active cycling and passive storage conditions. Solid electrolyte interphase growth continuously consumes mobile lithium ions, reducing available cell capacity.
Particle isolation and transition metal dissolution accelerate performance loss in demanding fast-charging applications.
Capacity Decay
Continuous side reactions convert active lithium into inactive chemical compounds within interphase layers on anode graphite particles. Main mechanisms of lithium ion degradation involve loss of lithium inventory and loss of active material host sites. Structural microcracks in high-nickel cathode particles cut off electrical contact, rendering sections of the electrode electrochemically inactive.
Resistance Rise
Solid electrolyte interphase thickening restricts lithium ion diffusion across the electrode boundary, raising cell impedance. Chemical manifestations of lithium ion degradation include solvent decomposition and electrolyte dry-out. Higher internal resistance increases heat generation during operation, accelerating secondary thermal degradation mechanisms.
Operating Limit
High operating temperatures and elevated states of charge drastically speed up chemical breakdown pathways. Prolonged exposure to low temperatures under high charging rates induces metallic lithium plating on anode surfaces. Avoiding extreme operating windows extends functional battery lifespan across automotive and stationary storage applications.
