Observation of Transition Metal Dissolution at Cathode Surface

Lei Yu, Tongchao Liu, Junwu Zhu, Jun Lu, Jianguo Wen
2020 Microscopy and Microanalysis  
Transition metal (TM) dissolution has been widely reported to severely degrade the anode, which is historically long accepted to be a singular root cause of battery capacity fading [1] . However, its impact on cathode behavior remains poorly understood. In spite of elaborate investigations into TM migration mechanisms on cathode surfaces, structural evolution of cathode materials undergoing TM dissolution and their interrelationships still have not been clear [2] . In this study, commercial
more » ... udy, commercial lithium manganite (LiMn2O4) is chosen as the investigated model material owing to its pronounced Mn(II) ion dissolution. By using aberration-corrected high-resolution TEM (HRTEM) and electron energy loss spectroscopy (EELS), it is found that many microcracks caused by structure phase transition and strain are generated on the cycled cathode particle surfaces. At the crack area, although there is no obvious lattice distinction, the electronic structure shows remarkable changes. The presence of Mn(II) indicates the TM dissolution prevails at the crack. The synergy effect of TM dissolution and irreversible structure damage may collectively accelerate cathode deterioration.
doi:10.1017/s1431927620014038 fatcat:63fdofoi2bdxreopkahsypx6w4