Dynamic impact of LiCoO2 electrodes for Li-ion battery aging evaluation

As Li-ion batteries (LIBs) see increasing usage for electric vehicles, the effect of transportation history on battery state-of-health remains unclear. In particular, the influence of dynamic impact on battery behavior is investigated in terms of its effect on battery aging. Standard LiCoO2 electrodes were dynamically impacted using a nano-impactor setup, and the relationship between impact cycle number (N = 0, 3, 12, and 1000) and electrochemical performance is studied. Li-ion half cells constructed from impacted electrodes display decreasing first cycle Coulombic and energy efficiency with number of impacts, with electrochemical impedance spectroscopy analysis revealing an increase in the chargetransfer resistance. Accelerated capacity fading through long-term cycling is observed for N = 1000 impacts, with significant voltage hysteresis and decay occurring by cycle 50. Additional ex-situ material characterization of cycled electrodes reveals a negative Raman shift by similar to 2-3 cm(-1) for the A(1g) and E-g bands for the N = 1000 case as compared to pristine LiCoO2, correlating to retention of material stress and electrochemical degradation via capacity fading. These results connect mechanical and electrochemical analysis of LIB electrodes, elucidating the relationship between dynamic impact and cell aging. (C) 2018 Elsevier Ltd. All rights reserved.