Lithium-Ion Battery Life Model with Electrode Cracking and Early-Life Break-in Processes

Kandler Smith, Paul Gasper, Andrew M. Colclasure, Yuta Shimonishi, Shuhei Yoshida
2021 Journal of the Electrochemical Society  
This paper develops a physically justified reduced-order capacity fade model from accelerated calendar-and cycle-aging data for 32 lithium-ion (Li-ion) graphite/nickel-manganese-cobalt (NMC) cells. The large data set reveals temperature-, charge C-rate-, depth-of-discharge-, and state of charge (SOC)-dependent degradation patterns that would be unobserved in a smaller test matrix. Model structure is informed by incremental capacity analysis that shows loss of lithium inventory and
more » ... al loss as the dominant capacity fade mechanisms. The model includes terms attributable to solid-electrolyte interface (SEI) growth, electrode cracking, cycling-driven acceleration of SEI growth, and "break-in" mechanisms that slightly decrease or increase available Li inventory early in life. The study explores what mathematical couplings of these mechanisms best describe calendar aging, cycle aging, and mixed calendar/cycle aging. Various approaches are discussed for extracting relevant stress factors from complex cycling profiles to predict lifetime during real-world battery loads using models trained on constant-current laboratory test results. The complexity of the present human-driven model identification process motivates future work in machine learning to more widely search and statistically discern the optimal model that correctly extrapolates capacity fade based on physical knowledge.
doi:10.1149/1945-7111/ac2ebd fatcat:s57wchhtufglni23itleaembbi