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

Publication Type

Journal Article

Date Published

02/2015

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.

Journal

Journal of the American Chemical Society

Volume

137

Year of Publication

2015

Issue

10

Pagination

3533-3539
Organization 
Research Areas