Operando nuclear magnetic resonance spectroscopy: Detection of the onset of metallic lithium deposition on graphite at low temperature and fast charge in a full Li-ion battery.

Lithium-ion batteries are at the core of the democratisation of electric transportation and portative electronic devices. However, fast and/or low temperature charge induce performance loss, mainly through lithium plating, a degrading mechanism. In this report, Li operando Nuclear Magnetic Resonance spectroscopy is used to detect the onset of metastable lithium deposits in an NMC622/graphite cell at 0 °C and fast charge.

Activation of anionic redox in d transition metal chalcogenides by anion doping.

Expanding the chemical space for designing novel anionic redox materials from oxides to sulfides has enabled to better apprehend fundamental aspects dealing with cationic-anionic relative band positioning. Pursuing with chalcogenides, but deviating from cationic substitution, we here present another twist to our band positioning strategy that relies on mixed ligands with the synthesis of the LiTiSSe solid solution series. Through the series the electrochemical activity displays a bell shape variation that peaks at 260 mAh/g for the composition x = 0.

Monitoring metallic sub-micrometric lithium structures in Li-ion batteries by in situ electron paramagnetic resonance correlated spectroscopy and imaging.

Monitoring the formation of dendrites or filaments of lithium is of paramount importance for Li-based battery technologies, hence the intense activities in designing in situ techniques to visualize their growth. Herein we report the benefit of correlating in situ electron paramagnetic resonance (EPR) spectroscopy and EPR imaging to analyze the morphology and location of metallic lithium in a symmetric Li/LiPF/Li electrochemical cell during polarization. We exploit the variations in shape, resonance field and amplitude of the EPR spectra to follow, operando, the nucleation of sub-micrometric Li particles (narrow and symmetrical signal) that conjointly occurs with the fragmentation of bulk Li on the opposite electrode (asymmetrical signal).

Local atomic and electronic structure in the LiVPO (F,O) tavorite-type materials from solid-state NMR combined with DFT calculations.

Li, P, and F solid-state nuclear magnetic resonance (NMR) spectroscopy was used to investigate the local arrangement of oxygen and fluorine in LiVPO F O materials, interesting as positive electrode materials for Li-ion batteries. From the evolution of the 1D spectra versus y, 2D Li radiofrequency-driven recoupling (RFDR) experiments combined, and a tentative signal assignment based on density functional theory (DFT) calculations, it appears that F and O are not randomly dispersed on the bridging X position between two X-VO -X octahedra (X = O or F) but tend to segregate at a local scale. Using DFT calculations, we analyzed the impact of the different local environments on the local electronic structure.