Direct observation of Mn-ion dissolution from LiMn2O4 lithium battery cathode to electrolyte
H. Nithya, Yoshiki Iwai, Masato Ohzu, Sebastian Brox, Arunkumar Dorai, Reiji Takekawa, Naoaki Kuwata, Junichi Kawamura, Martin Winter
Abstract
The degradation of lithium-ion batteries has become a concerning issue. One problem is metal ion dissolution from the cathode material, such as Mn2+ dissolution from spinel-type LiMn2O4 (LMO). However, direct observation of the dissolution process has yet to be reported. Here, we establish in-situ 1H nuclear magnetic resonance imaging (MRI) measurement as an efficient technique to observe Mn2+ dissolution from a model lithium battery with LMO as the cathode. We observe an increase in the MRI signal intensity near the cathode, confirming the dissolution of Mn2+ from the cathode to the electrolyte. Moreover, we show that Mn2+ dissolution from LMO can be suppressed using an appropriate choice of electrolytes. We believe the method developed here can answer the long-time unanswered question of when, where, and how the metal ion dissolution occurs in the lithium-ion battery electrode and can be extended to other electrochemical systems. Metal ion dissolution from the cathode is a major issue for lithium-ion battery degradation. Here, 1H nuclear magnetic resonance imaging was demonstrated as an efficient technique to directly observe Mn2+ dissolution from a LiMn2O4 cathode of a model lithium battery.