The Formation Mechanism of Fluorescent Metal Complexes at the LixNi0.5Mn1.5O4 - δ/Carbonate Ester Electrolyte Interface

The Formation Mechanism of Fluorescent Metal Complexes at the LixNi0.5Mn1.5O4 - δ/Carbonate Ester Electrolyte Interface

TitleThe Formation Mechanism of Fluorescent Metal Complexes at the LixNi0.5Mn1.5O4 - δ/Carbonate Ester Electrolyte Interface
Publication TypeJournal Article
Year of Publication2015
AuthorsAngélique Jarry, Sébastien Gottis, Young-Sang Yu, Josep Roque-Rosell, Chunjoong Kim, Jordi Cabana, John B Kerr, Robert Kostecki
JournalJournal of the American Chemical Society
Volume137
Issue10
Pagination3533-3539
Date Published02/2015
Abstract

Electrochemical oxidation of carbonate esters at the LixNi0.5Mn1.5O4−δ/electrolyte interface results in Ni/Mn dissolution and surface film formation, which negatively affect the electrochemical performance of Li-ion batteries. Ex situ X-ray absorption (XRF/XANES), Raman, and fluorescence spectroscopy, along with imaging of LixNi0.5Mn1.5O4−δ positive and graphite negative electrodes from tested Li-ion batteries, reveal the formation of a variety of MnII/III and NiII complexes with β-diketonate ligands. These metal complexes, which are generated upon anodic oxidation of ethyl and diethyl carbonates at LixNi0.5Mn1.5O4−δ, form a surface film that partially dissolves in the electrolyte. The dissolved MnIII complexes are reduced to their MnII analogues, which are incorporated into the solid electrolyte interphase surface layer at the graphite negative electrode. This work elucidates possible reaction pathways and evaluates their implications for Li+ transport kinetics in Li-ion batteries.

DOI10.1021/ja5116698