SEI Formation on TiO2 Rutile

X-ray photoelectron spectroscopy (XPS) and symmetric electrochemical impedance spectroscopy (EIS) are carried out to identify and determine the nature of the solid electrolyte interface (SEI) formation on TiO2 rutile anodes in lithium ion batteries. The recorded XPS spectra (O1s, C1s, P2p and Li1s and Ti2p) evidence an SEI layer formation at 0.8 V vs. Li/Li+ in a TiO2/Li cell with a lithium reference and an organic electrolyte (LiPF6 in EC : DMC (1 : 1 by wt%)). When the cell is discharged down to 0.1 V, the SEI mainly consists of ether and carbonyl groups and some alcohol or alkoxide groups. Upon charge the SEI additionally evidences some carboxylic groups. EIS measurements exhibit an additional RQ element at 0.8 V, supporting the formation of the SEI at this potential. The EIS evaluation shows that the SEI is mainly formed in the first cycle but evolves further on in the following cycles

Locally enhanced conductivity due to the tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces

The ability to control materials properties through interface engineering is demonstrated by the appearance of conductivity at the interface of certain insulators, most famously the {001} interface of the band insulators LaAlO$_{3}$ and TiO$_{2}$-terminated SrTiO$_{3}$ (STO). Transport and other measurements in this system show a plethora of diverse physical phenomena. To better understand the interface conductivity, we used scanning superconducting quantum interference device microscopy to image the magnetic field locally generated by current in an interface. At low temperature, we found that the current flowed in conductive narrow paths oriented along the crystallographic axes, embedded in a less conductive background. The configuration of these paths changed on thermal cycling above the STO cubic-to-tetragonal structural transition temperature, implying that the local conductivity is strongly modified by the STO tetragonal domain structure. The interplay between substrate domains and the interface provides an additional mechanism for understanding and controlling the behaviour of heterostructures

Cu/Li4Ti5O12 scaffolds as superior anodes for lithium-ion batteries

Nanostructured active materials with both high-capacity and high-rate capability have attracted considerable attention, but they remain a great challenge to be realized. Herein, we report a new route to fabricate a bicontinuous Cu/Li4Ti5O12 scaffold that consists of Li4Ti5O12 nanoparticles (LTO NPs) with highly exposed (111) facets and nanoporous Cu scaffolds, which enable simultaneous high-capacity and high-rate lithium storage. It is a 'one stone, two birds' strategy. When tested as the anode in lithium-ion batteries LIBs, Cu/LTO showed superior performance, such as a lifespan greater than 2000 cycles and an ultrafast charging time (<45 s). Notably, the ultrahigh capacity slightly larger than the theoretical value was also observed in Cu/LTO at low current density. Density functional theory calculations and detailed characterizations revealed that the highly exposed (111) facets on the edge are the reason for its unique storage mechanism (8a+16c), which is different from the transition between 8a and 16c in bulk LTO