TY - JOUR

T1 - Formation of the Solid Electrolyte Interphase at Constant Potentials

T2 - a Model Study on Highly Oriented Pyrolytic Graphite

AU - Antonopoulos, Byron Konstantinos

AU - Maglia, Filippo

AU - Schmidt-Stein, Felix

AU - Hoster, Harry Ernst

AU - Schmidt, Jan Philipp

N1 - This is the peer reviewed version of the following article: B. K. Antonopoulos, F. Maglia, F. Schmidt-Stein, J. P. Schmidt, H. E. Hoster, Batteries & Supercaps 2018, 1, 110 which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/batt.201800029/abstract This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

PY - 2018/9

Y1 - 2018/9

N2 - The solid electrolyte interphase (SEI) on graphite anodes is a key enabler for rechargeable lithium ion batteries (LIBs). It ensures that only Li+ ions and no damaging electrolyte components enter the anode and hinders electrolyte decomposition. Its growth should be confined to the initial SEI formation process and stop once the battery is in operation to avoid capacity/power loss. In technical LIB cells, the SEI is formed at constant current, with the potential of the graphite anode slowly drifting from higher to lower voltages. SEI formation rate, composition, and structure depend on the potential and on the chemical properties of the anode surface. Here, we characterize SEIs formed at constant potentials on the chemically inactive basal plane of highly oriented pyrolytic graphite (HOPG). X‐ray photoemission spectroscopy (XPS) detects carbonate‐species only at lower formation potentials. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) with Fc/Fc+ as an electrochemical probe demonstrate how the formation potential influences ion transport and electrochemical kinetics to and at the anode surface, respectively. Breaking the EIS data down to a Distribution of Relaxation Times (DRT) reveals distinct kinetics and transport related peaks with varying Arrhenius‐type temperature dependencies. We discuss our findings in the context of previous electrochemical studies and existing SEI models and of SEI formation protocols suitable for industry.

AB - The solid electrolyte interphase (SEI) on graphite anodes is a key enabler for rechargeable lithium ion batteries (LIBs). It ensures that only Li+ ions and no damaging electrolyte components enter the anode and hinders electrolyte decomposition. Its growth should be confined to the initial SEI formation process and stop once the battery is in operation to avoid capacity/power loss. In technical LIB cells, the SEI is formed at constant current, with the potential of the graphite anode slowly drifting from higher to lower voltages. SEI formation rate, composition, and structure depend on the potential and on the chemical properties of the anode surface. Here, we characterize SEIs formed at constant potentials on the chemically inactive basal plane of highly oriented pyrolytic graphite (HOPG). X‐ray photoemission spectroscopy (XPS) detects carbonate‐species only at lower formation potentials. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) with Fc/Fc+ as an electrochemical probe demonstrate how the formation potential influences ion transport and electrochemical kinetics to and at the anode surface, respectively. Breaking the EIS data down to a Distribution of Relaxation Times (DRT) reveals distinct kinetics and transport related peaks with varying Arrhenius‐type temperature dependencies. We discuss our findings in the context of previous electrochemical studies and existing SEI models and of SEI formation protocols suitable for industry.

KW - SEI Formation

KW - Highly Oriented Pyrolitic Graphite

KW - Model Electrode Surface

KW - electrochemistry

KW - materials science

KW - outer sphere reaction

U2 - 10.1002/batt.201800029

DO - 10.1002/batt.201800029

M3 - Journal article

VL - 1

SP - 110

EP - 121

JO - Batteries & Supercaps

JF - Batteries & Supercaps

IS - 3

ER -