Curious Case of Positive Current Collectors: Corrosion and Passivation at High Temperature

In the evaluation of compatibility of different components of cell for high-energy and extreme-conditions applications, the highly focused are positive and negative electrodes and their interaction with electrolyte. However, for high-temperature application, the other components are also of significant influence and contribute toward the total health of battery. In present study, we have investigated the behavior of aluminum, the most common current collector for positive electrode materials for its electrochemical and temperature stability. For electrochemical stability, different electrolytes, organic and room temperature ionic liquids with varying Li salts (LiTFSI, LiFSI), are investigated. The combination of electrochemical and spectroscopic investigations reflects the varying mechanism of passivation at room and high temperature, as different compositions of decomposed complexes are found at the surface of metals

Hybrid Multiferroic Nanostructure with Magnetic–Dielectric Coupling

The development of methods to economically synthesize single wire structured multiferroic systems with room temperature spin–charge coupling is expected to be important for building next-generation multifunctional devices with ultralow power consumption. We demonstrate the fabrication of a single nanowire multiferroic system, a new geometry, exhibiting room temperature magnetodielectric coupling. A coaxial nanotube/nanowire heterostructure of barium titanate (BaTiO₃, BTO) and cobalt (Co) has been synthesized using a template-assisted method. Room temperature ferromagnetism and ferroelectricity were exhibited by this coaxial system, indicating the coexistence of more than one ferroic interaction in this composite system

Thermally Assisted Nonvolatile Memory in Monolayer MoS₂ Transistors

We demonstrate a novel form of thermally-assisted hysteresis in the transfer curves of monolayer MoS₂ FETs, characterized by the appearance of a large gate-voltage window and distinct current levels that differ by a factor of ∼10². The hysteresis emerges for temperatures in excess of 400 K and, from studies in which the gate-voltage sweep parameters are varied, appears to be related to charge injection into the SiO₂ gate dielectric. The thermally-assisted memory is strongly suppressed in equivalent measurements performed on bilayer transistors, suggesting that weak screening in the monolayer system plays a vital role in generating its strongly sensitive response to the charge-injection process. By exploiting the full features of the hysteretic transfer curves, programmable memory operation is demonstrated. The essential principles demonstrated here point the way to a new class of thermally assisted memories based on atomically thin two-dimensional semiconductors

Conduction Mechanisms in CVD-Grown Monolayer MoS₂ Transistors: From Variable-Range Hopping to Velocity Saturation

We fabricate transistors from chemical vapor deposition-grown monolayer MoS₂ crystals and demonstrate excellent current saturation at large drain voltages (<i>V</i>_d). The low-field characteristics of these devices indicate that the electron mobility is likely limited by scattering from charged impurities. The current–voltage characteristics exhibit variable range hopping at low <i>V</i>_d and evidence of velocity saturation at higher <i>V</i>_d. This work confirms the excellent potential of MoS₂ as a possible channel-replacement material and highlights the role of multiple transport phenomena in governing its transistor action