In Situ Mass Spectrometric Determination of Molecular Structural Evolution at the Solid Electrolyte Interphase in Lithium-Ion Batteries.
Dynamic structural and chemical evolution at solid-liquid electrolyte interface is always a mystery for a rechargeable battery due to the challenge to directly probe a solid-liquid interface under reaction conditions. We describe the creation and usage of in situ liquid secondary ion mass spectroscopy (SIMS) for the first time to directly observe the molecular structural evolution at the solid-liquid electrolyte interface for a lithium (Li)-ion battery under dynamic operating conditions. We have discovered that the deposition of Li metal on copper electrode leads to the condensation of solvent molecules around the electrode. Chemically, this layer of solvent condensate tends to be depleted of the salt anions and with reduced concentration of Li(+) ions, essentially leading to the formation of a lean electrolyte layer adjacent to the electrode and therefore contributing to the overpotential of the cell. This observation provides unprecedented molecular level dynamic information on the initial formation of the solid electrolyte interphase (SEI) layer. The present work also ultimately opens new avenues for implanting the in situ liquid SIMS concept to probe the chemical reaction process that intimately involves solid-liquid interface, such as electrocatalysis, electrodeposition, biofuel conversion, biofilm, and biomineralization.
Zihua
Z
Zhu
School of Physics, State Key Laboratory of Crystal Materials & Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University , Jinan 250100, China.
Yufan
Y
Zhou
Pengfei
P
Yan
Rama Sesha
RS
Vemuri
Wu
W
Xu
Rui
R
Zhao
School of Physics, State Key Laboratory of Crystal Materials & Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University , Jinan 250100, China.
Xuelin
X
Wang
Suntharampillai
S
Thevuthasan
Donald R
DR
Baer
Chong-Min
CM
Wang
In situ liquid SIMS; SEI layers; lithium ion battery; molecular structural evolution; solid−liquid interface