Toward Characterization of Interphases in Batteries.

Electrode/electrolyte interfaces are the most important and least understood components of Li-ion and next-generation batteries. An improved understanding of interphases in batteries will undoubtedly lead to breakthroughs in the field. Traditionally, evaluating those interphases involves using surface sensitive and/or imaging techniques.

Mechanistic understanding of the correlation between structure and dynamics of liquid carbonate electrolytes: impact of polarization.

Liquid electrolyte design and modelling is an essential part of the development of improved lithium ion batteries. For mixed organic carbonates (ethylene carbonate (EC) and ethyl-methyl carbonate (EMC) mixtures)-based electrolytes with LiPF as salt, we have compared a polarizable force field with the standard non-polarizable force field with and without charge rescaling to model the structural and dynamic properties. The result of our molecular dynamics simulations shows that both polarizable and non-polarizable force fields have similar structural factors, which are also in agreement with X-ray diffraction experimental results.

Operando Monitoring the Insulator-Metal Transition of LiCoO.

LiCoO (LCO) is one of the most-widely used cathode active materials for Li-ion batteries. Even though the material undergoes an electronic two-phase transition upon Li-ion cell charging, LCO exhibits competitive performance in terms of rate capability. Herein the insulator-metal transition of LCO is investigated by Raman spectroscopy complemented with DFT calculations and a developed sampling volume model.

Direct Observation of Double Layer Charging and Early Solid Electrolyte Interphase Formation in Li-Ion Battery Electrolytes.

The solid electrolyte interphase (SEI) is the most critical yet least understood component to guarantee stable and safe operation of a Li-ion cell. Herein, the early stages of SEI formation in a typical LiPF and organic carbonate-based Li-ion electrolyte are explored by surface-enhanced Raman spectroscopy, on-line electrochemical mass spectrometry, and electrochemical quartz crystal microbalance. The electric double layer is directly observed to charge as Li solvated by ethylene carbonate (EC) progressively accumulates at the negatively charged electrode surface.