Lithium Transport through Ultrathin Silicon Layers

This contribution presents non-destructive measurements of lithium transport parameters (diffusivity, permeability) in nanometer sized silicon layers done by a novel neutron reflectometry (NR) based approach [4]

15-N NRA Data for article: Tracer diffusion in proton-exchanged congruent LiNbO3 crystals as a function of hydrogen content

Raw data from 15N NRA measurements including data evaluation

In-operando neutron reflectometry studies on lithium insertion into silicon electrodes of Li-ion batteries

Lithium ion incorporation into amorphous silicon electrodes was monitored via in-op-erando neutron reflectometry in real-time during battery cell operation. Recent results of cyclic voltammetry experiments are presented. These experiments enable us to mon-itor the enormous volume expansion, the formation and evolution of the SEI (solid elec-trolyte interphase), the determination of irreversible capacity losses and voltage hyste-resis effects during cycling

Lithium Transport through Ultrathin Silicon Layers

This contribution presents non-destructive measurements of lithium transport parameters (diffusivity, permeability) in nanometer sized silicon layers done by a novel neutron reflectometry (NR) based approach [4]

Electrochemical lithiation of silicon electrodes neutron reflectometry and secondary ion mass spectrometry investigations

In situ neutron reflectometry and ex situ secondary ion mass spectrometry in combination with electrochemical methods were used to study the lithiation of amorphous silicon electrodes. For that purpose specially designed closed three electrode electrochemical cells with thin silicon films as the working electrode and lithium as counter and reference electrodes were used. The neutron reflectometry results obtained in situ during galvanostatic cycling show that the incorporation, redistribution and removal of Li in amorphous silicon during a lithiation cycle can be monitored. It was possible to measure the volume modification during lithiation, which is found to be rather independent of cycle number, current density and film thickness and in good agreement with first principles calculations as given in literature. Indications for an inhomogeneous lithiation mechanism were found by secondary ion mass spectrometry measurements. Lithium tracer diffusion experiments indicate that the diffusivities inside the lithiated region D gt; 10 amp; 8722;15 m2 s amp; 8722;1 are considerably higher than in pure amorphous silicon as known from literature. This suggests a kinetics based explanation for the occurrence of an inhomogeneous lithiation mechanis

Lithium insertion into silicon electrodes studied by cyclic voltammetry and operando neutron reflectometry

Operando neutron reflectometry measurements were carried out to study the insertion of lithium into amorphous silicon film electrodes during cyclic voltammetry CV experiments at a scan rate of 0.01 mV s amp; 8722;1. The experiments allow mapping of regions where significant amounts of Li are incorporated released from the electrode and correlation of the results to modifications of characteristic peaks in the CV curve. High volume changes up to 390 accompanied by corresponding modifications of the neutron scattering length density which is a measure of the average Li fraction present in the electrode are observed during electrochemical cycling for potentials below 0.3 V lithiation and above 0.2 V delithiation , leading to a hysteretic behaviour. This is attributed to result from mechanical stress as suggested in the literature. Formation and modification of a surface layer associated with the solid electrolyte interphase SEI were observed during cycling. Within the first lithiation cycle the SEI grows to 120 for potentials below 0.5 V. Afterwards a reversible and stable modification of the SEI between 70 delithiated state and 120 lithiated state takes plac

Neutron reflectometry studies on the lithiation of amorphous silicon electrodes in lithium ion batteries

Neutron reflectometry is used to study in situ the intercalation of lithium into amorphous silicon electrodes. The experiments are done using a closed three electrode electrochemical cell setup. As a working electrode, an about 40 nm thick amorphous silicon layer is used that is deposited on a 1 cm thick quartz substrate coated with palladium as a current collector. The counter electrode and the reference electrode are made of lithium metal. Propylene carbonate with 1 M LiClO4 is used as an electrolyte. The utility of the cell is demonstrated during neutron reflectometry measurements where Li is intercalated at a constant current of 100 [small mu ]A 7.8 [small mu ]A cm 2 for different time steps. The results show a that the change in Li content in amorphous silicon and the corresponding volume expansion can be monitored, b that the formation of the solid electrolyte interphase becomes visible and c that an irreversible capacity loss is presen