Mitigation of grain boundary resistance in La2/3-xLi3xTiO3 perovskite as an electrolyte for solid-state Li-ion batteries

In this work, we report that modification of the chemical composition of grain boundaries of La2/3-xLi3xTiO3 double perovskite, one of the most promising Li-ion conducting solid electrolytes, can be a convenient and versatile way of controlling the space charge potential, leading to a mitigated electrical resistance of the grain boundaries. Two groups of additives are investigated: lithium-enriching agents (Li3BO3, LiF) and 3d metal ions (Co2+, Cu2+), both expected to reduce the Schottky barrier. It is observed that Li-containing additives work effectively at a higher sintering temperature of 1250 °C. Regarding copper, it shows a much stronger positive impact at lower temperature, 1150 °C, while the addition of cobalt is always detrimental. Despite overall complex behavior, it is documented that the decreased space charge potential plays a more important role in the improvement of lithium conduction than the thickness of the grain boundaries. Among the proposed additives, modification of La2/3-xLi3xTiO3 by 2 mol.% Cu2+ results in the space charge potential reduction by 32 mV in relation to the reference sample, and the grain boundary specific conductivity increase by 80%, as measured at 30 °C. Introduced additive allows to obtain a similar effect on the conductivity as elevating the sintering temperature, which can facilitate manufacturing procedure. Graphic abstract

Influence of Ce3+ polarons on grain boundary space-charge in proton conducting Y-doped BaCeO3

Ce3+ polarons associated with oxygen vacancies in the grain boundary core lowers the space-charge potential and may enhance n-type conduction.

Isn't the space-charge potential in ceria-based solid electrolytes largely overestimated?

The height of the potential barrier at the grain boundary in concentrated ceria solid solutions found in the literature is largely overestimated.

Experimental evidence for space charge segregation in Nb-doped BaTiO3

There is ample experimental evidence demonstrating space charge segregation in acceptor-doped BaTiO3. However there is still some controversy regarding donor-doped BaTiO3. Considering the space charge segregation theory in BaTiO3, the calculated driving force for space charge segregation is larger in acceptor-doped cases than in donor-doped cases. This result explains why acceptor segregation can be easily detected. However, a significant concentration of donors can also cause donor segregation. In donor and acceptor codoped BaTiO3, the grain sizes are very small, and donor segregation can be detected for compositions inducing a large space charge potential. In addition, in compositions that induced a small space charge potential, the grain sizes are very large, and donor segregation is not detected, although the total doping concentration is larger. This phenomenon means that donor segregation is caused by the space charge potential rather than misfit strain energy.

Effect of chamber pressure induced space charge potential on ion acceleration in laser produced plasma

The acceleration of ions (∼108 cm/s) has been observed in the laser produced plasma expanding across an uniform magnetic field at low laser irradiance (∼5 × 1012 W/cm2). This acceleration was found correlated with the onset of instabilities in the plasma and decrease in the slope of X-ray emission with laser intensity. A large enhancement in the X-ray emission (E > 2 KeV) from plasma in the presence of magnetic field supports the observation of ion acceleration. An increase in the number of ions was noticed in the pressure range in which enhancement in the self-generated spontaneous magnetic field has already been established. Even scaling of both the variations with chamber pressure during rising part was found in close agreement, which further supports the correlation. The possibility of an external magnetic field in triggering the acceleration and space charge potential in generating a correlation (between ion acceleration and self-generated spontaneous magnetic field) has been discussed.

Dynamics Of Grain Boundary Space-Charge Potential In Electroceramics

A large number of bulk and thin-film electroceramic systems contain electrically active interfaces which dictate the various useful electronic properties of these devices. The electrical activity of these interfaces stems from a complex interplay among various interfacial attribute but often involves formation of some form of electrostatic potential at the interfaces which is modified under applied bias of current and/or voltage.Figure la schematically shows charge distribution at a model grain boundary (GB), while Figure 1(b) shows its corresponding potential distribution. As shown in Figure 1(c), the energy band structure bends opposite to this built-in potential, causing a downward shift at the grain boundary . The difficulty with evaluating the Schottky barrier model, which is often invoked to explain GB electrical activity, is that the charge density distribution and therefore the band bending is expected to dynamically alter as bias is applied across the grain boundary. This variation adds another level of complexity to theoretical descriptions of the barrier behavior