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In Situ Measurement of Solid Electrolyte Interphase Evolution on Silicon Anodes Using Atomic Force Microscopy
Author(s) -
Yoon Insun,
Abraham Daniel P.,
Lucht Brett L.,
Bower Allan F.,
Guduru Pradeep R.
Publication year - 2016
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201600099
Subject(s) - electrolyte , materials science , silicon , ethylene carbonate , lithium (medication) , propylene carbonate , electrochemistry , electrochemical potential , interphase , electrode , chemical engineering , amorphous solid , analytical chemistry (journal) , crystallography , chemistry , optoelectronics , organic chemistry , medicine , biology , engineering , genetics , endocrinology
In situ measurements of the growth of solid electrolyte interphase (SEI) layer on silicon and the lithiation‐induced volume changes in silicon in lithium ion half‐cells are reported. Thin film amorphous silicon electrodes are fabricated in a configuration that allows unambiguous separation of the total thickness change into contribution from SEI thickness and silicon volume change. Electrodes are assembled into a custom‐designed electrochemical cell, which is integrated with an atomic force microscope. The electrodes are subjected to constant potential lithiation/delithiation at a sequence of potential values and the thickness measurements are made at each potential after equilibrium is reached. Experiments are carried out with two electrolytes—1.2 m lithium hexafluoro‐phosphate (LiPF 6 ) in ethylene carbonate (EC) and 1.2 m LiPF 6 in propylene carbonate (PC)—to investigate the influence of electrolyte composition on SEI evolution. It is observed that SEI formation occurs predominantly during the first lithiation and the maximum SEI thickness is ≈17 and 10 nm respectively for EC and PC electrolytes. This study also presents the measured Si expansion ratio versus equilibrium potential and charge capacity versus equilibrium potential; both relationships display hysteresis, which is explained in terms of the stress–potential coupling in silicon.