Understanding Degradation at the Lithium-Ion Battery Cathode/Electrolyte Interface: Connecting Transition-Metal Dissolution Mechanisms to Electrolyte Composition

Di Huang, Chaiwat Engtrakul, Sanjini Nanayakkara, David W. Mulder, Sang Don Han, Meng Zhou, Hongmei Luo, Robert C. Tenent

Research output: Contribution to journalArticlepeer-review

34 Scopus Citations

Abstract

Lithium transition-metal oxides (LiMn2O4 and LiMO2 where M = Ni, Mn, Co, etc.) are widely applied as cathode materials in lithium-ion batteries due to their considerable capacity and energy density. However, multiple processes occurring at the cathode/electrolyte interface lead to overall performance degradation. One key failure mechanism is the dissolution of transition metals from the cathode. This work presents results combining scanning electrochemical microscopy with inductively coupled plasma (ICP) and electron paramagnetic resonance (EPR) spectroscopies to examine cathode degradation products. Our effort employs a LiMn2O4 (LMO) thin film as a model cathode to monitor the Mn dissolution process without the potential complications of conductive additive and polymer binders. We characterize the electrochemical behavior of LMO degradation products in various electrolytes, paired with ICP and EPR, to better understand the properties of Mn complexes formed following metal dissolution. We find that the identity of the lithium salt anions in our electrolyte systems [ClO4-, PF6-, and (CF3SO2)2N-] appears to affect the Mn dissolution process significantly as well as the electrochemical behavior of the generated Mn complexes. This implies that the mechanism for Mn dissolution is at least partially dependent on the lithium salt anion.

Original languageAmerican English
Pages (from-to)11930-11939
Number of pages10
JournalACS Applied Materials and Interfaces
Volume13
Issue number10
DOIs
StatePublished - 17 Mar 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-79520

Keywords

  • cathode/electrolyte interface
  • LiMnO
  • Mn dissolution
  • polymer-assisted deposition
  • scanning electrochemical microscopy

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